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From Wikipedia, the free encyclopedia

"Genus Homo" redirects here. For the novel by L. Sprague de Camp and P. Schuyler Miller, see Genus Homo (novel).
For other uses, see Homo (disambiguation).
Homo
Temporal range: Piacenzian-Present, 2.865–0 Ma
Homo georgicus.jpg
Reconstruction of Homo erectus georgicus (Élisabeth Daynès, Musée de Préhistoire, Quinson, France)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Family: Hominidae
Tribe: Hominini
Genus: Homo
Linnaeus, 1758
Type species
Homo sapiens
Linnaeus, 1758
Species

Homo sapiens
Homo erectus
Homo floresiensis
Homo habilis
Homo heidelbergensis
Homo naledi
Homo neanderthalensis
other species or subspecies suggested, see below.

Synonyms

Homo is the genus that comprises the species Homo sapiens, which includes modern humans, as well as several extinct species classified as ancestral to or closely related to modern humans, most notably Homo erectus. The genus is between 2 and 3 million years old, taken to emerge with the appearance of Homo habilis.[1] It is derived from the genus Australopithecus, which itself had previously split from the lineage of Pan, the chimpanzees.[2] Taxonomically, Homo is the only genus assigned to the subtribe Hominina which, with the subtribes Australopithecina and Panina, comprise the tribe Hominini (see evolutionary tree below). All species of the genus Homo plus those species of the australopithecines that arose after the split from Pan are called hominins.

Homo erectus appeared about two million years ago in East Africa (where it is dubbed Homo ergaster) and, in several early migrations, it spread throughout Africa and Eurasia. It was likely the first hominin to live in a hunter-gatherer society and to control fire. An adaptive and successful species, Homo erectus persisted for almost 2 million years before suddenly becoming extinct about 70,000 years ago (0.07 Ma)—perhaps a casualty of the Toba supereruption catastrophe.

Homo sapiens sapiens, or anatomically modern humans, emerged about 200,000 years ago (0.2 Ma) in East Africa (see Omo remains). Modern humans migrated from Africa as recently as 60,000 years ago, and during Upper Paleolithic times they spread throughout Africa, Eurasia, Oceania, and the Americas; and they encountered archaic humans en route of their migrations. Homo sapiens sapiens is considered the only surviving species and subspecies of the genus Homo; archaic humans survived until about 40,000 years ago (see H. neanderthalensis),[3] and possibly until as late as the times of the Epipaleolithic culture (about 12,000 years ago). DNA analysis provides some evidence of interbreeding between archaic and modern humans.[4][5]

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Transcription

- [Announcer] This UCSD TV program is presented by University of California Television. Like what you learn? Visit our website, or follow us on Facebook and Twitter to keep up with the latest programs. ♪ [music] ♪ - [Narrator] We are the paradoxical ape. Bipedal, naked large-brained. Long the master of fire, tools and language, but still trying to understand ourselves. Aware that death is inevitable, yet filled with optimism. We grow up slowly. We hand down knowledge. We empathize and deceive. We shape the future from our shared understanding of the past. CARTA brings together experts from diverse disciplines to exchange insights on who we are and how we got here. An exploration made possible by the generosity of humans like you. ♪ [music] ♪ - [William] Good afternoon everyone and thank you to the organizers here of CARTA for inviting me to participate and thank all of you, a great crowd, for coming out to see this fascinating topic explored. I tend sometimes to be accused of nihilism with regard to the origin of Homo because my view is we actually know nothing about the origin of Homo, just saying. And the reason is simple in my view; is that while it is true that we have a pretty good fossil record of the genus Homo, the Homo lineage as Bernard just finished explaining, by around 2 million years ago with some diversity and different adaptive packages in different species: erectus, habilis, rudolfensis. On the assumption that these three forms shared a common ancestor at some point. That common ancestor lived older than 2 million years ago in a period of time in which we have not a fender and a tire and a piece of gear shift, but in which we have a fragment of tire thread, which we have a fragment of a headlight. And we are trying to reconstruct an evolutionary history of a group for which we basically have a car wreck. And this is what we have to solve, this is the problem we have to solve and this comes from field work and I'm going to illustrate for you today in my view where I think the genus, the Homo lineage arose and where we have to re-double our efforts for increasing the representation of this lineage older than 2 million years ago. Now, as Bernard ably suggested, the modern history of the study of the evolution of the genus Homo really begins with Louis Leakey and colleagues and the recognition of the species, Homo habilis in 1964 based on material from Bed I in Olduvai Gorge dated to between around 1.7 and 1.75 million years, they discerned in the type specimen of the species older by Hominid VII what they thought was a human-like dextrous ability in the hands, they discerned a notable increase in endocranial volume, brain size, in relation to then known Australopithecus species, mostly from southern Africa and a reduction in tooth size which they saw as emblematic of an overall gracilization of the chewing apparatus in almost a human-like arrangement. And putting these three characteristics together with the plentiful stone tools that had been recovered for years in these sediments, they arrived at the conclusion that this species, habilis, belonged near the base of the genus Homo. So convinced were they of this conclusion that Philip Tobias, one the co-authors of the species, was able to write in 1965 that Homo habilis represented that last remaining major gap in the pleistocene evolution of the genus Homo, “of the story of human evolution, ” to quote him directly. And in this phylogeny shown here from one of Tobias' papers, you can see the genus Homo is represented as a single, gradually evolving line characterized by uniquely human characteristics related to large brain size, reduced canine teeth, a perfection of bipedal locomotion as we now see it, a slowing down of the growth trajectory, technology, language and so forth. This was a package of characteristics seen in modern humans and thought to go back in time to at least 2 million years as an integrated whole, along this slowly emerging lineage culminating in Homo sapiens. The problem was of course is that older than 2 millions years ago, there was virtually no fossil record that could be confidently associated uniquely with our lineage. And so whether these characteristics emerged piecemeal, step-wise and therefore each demanding a separate explanation for origin, or whether they emerged as a package together, where one explanation would take care of them all, could not be discerned. Now a lot has happened, as Bernard has pointed out in the years since early 1960s. And beginning in the 1980s, in large part due to the work that he and others have done in those years, we now see the genus Homo as a much more complicated array of species. In my view, there are at least three broadly contemporaneous forms present at around 2 million years ago whereas in 1964, the Leakeys would have said there's one in the genus Homo: Homo rudolfensis, Homo habilis and Homo erectus. And one of the lessons that we have learned from the appreciation of greater diversity in our own genus at this period of time, is the idea that there is not one adaptive package that can describe them all, but there are perhaps multiple ones. And the question is which, if any, are germane to the origin of the lineage itself? Or, are they all, in one form or another, subsequent developments to the establishment of the lineage? Following on Bernard's talking about Toyotas and Clades, my appreciation, my rendering of the information available from these three forms between around 1.7 and 2 million years ago is that they do, in fact, constitute a monophyletic group. This is not the place to go into a detailed rendition about the evidence for it, but I think it speaks fairly clearly to the idea that these three at 2 million did in fact share a single unified ancestry predating that time period, moving back towards the 3 million year mark. And the question is, where is it? And who was it? And here's where we run up against a roadblock. Now, why is this important more than just for the purposes of putting cladograms or phylogenies on the page is because in the last decade or two, information from global climate change, paleo-climatic change, has made it clear that the tim period in which many people suspect the Homo lineage arose was one of a very widespread, impactful change in global climate, creating an expansion of ice sheets, reduction in sea levels, drying out of the African interior. And that time period has been focused right after the 3 million year mark; 2.8, 2.7 and so forth. And that drying out of Africa has been seen as motive in the origin of the robust Australopithecines, the origin of the genus Homo, even to stone tool manufacture. This has become the prevailing hypothesis that the complexification, if you will, of hominids and the origin of technology is all associated with the local impacts of these global changes. The problem is that there's no fossil evidence for the genus Homo that is informative on exactly what those changes were at this particular point in time. We do have of course Oldowan tools at around 2.6 million. And as Bernard and others have pointed out, perhaps that is a proxy for the genus Homo or maybe it isn't. It's not outside the realm of possibility given what we know about how chimpanzees can make tools that some Australopithecus is capable of making them, too. So, questions and an absence of evidence. And here is the sum total of the fossil record of the genus Homo between 2- and 2.5 million years ago. It would fit in a shoe box and leave room for a decent pair of shoes. All of these fossils have been promoted by one person or another, one group or another as identifying the genus Homo older than 2.0 million years ago and all of them have been doubted. And I'm not going to go through them here to point out the weaknesses and strengths of the various arguments, other than to say that the very fact that there's debate can be traced to the fact that there's relatively little evidence. And this is why groups return to Africa, go to the field to African sites, in East Africa, in South Africa all the time focusing on this time period which, in my view, is one of the most intriguing of all the time periods in human evolution to increase our understanding of the fossil record. One area where the group from The Institute of Human Origins which I direct at ASU has been focusing on, of course, for years is Ethiopia. We've worked at the Lucy site more or less continuously since 1990. And colleagues of mine, Dr. Kaye Reed at ASU and Chris Campisano and others, have expanded the work, the IHO work in Ethiopia, to a place called Ledi-Geraru as seen here as slightly north and east of the Hadar area. What attracted them to this area? Two things, knowledge that the environments represented by the sediments in this area looked different from those that were very common and well-understood in the Lucy time period, older than 3 million, some 20, 30 kilometers away at Hadar. And second, the suspicion verified since then that the rocks may actually represent a slightly younger time period and that's important because at Hadar, as you will see, we have Lucy species, Australopithecus afarensis up to about 3 million years and then we jump across three quarters of a million years and we have a jaw of Homo with some stone tools at 2.3 million. Lucy, Homo; older, younger. Gap in the middle, let's try to fill it. And that was their mission. Now, in the lower Awash Valley, these areas around Hadar and middle Ledi and Gona and Dikika and Woranso-Mille, there are excellent sediments going backwards in time from around 3 million years ago. And we have an excellent set of sediments in places like Gona and Hadar that take us forward from around 2.5 million years ago. It is the time period in between that is critical and is germane to the questions about where the three forms of Homo that we know of at 2 million perhaps emerged from? And these sediments are present amply, now well-studied in the Ledi-Geraru area spanning in time from around 2.8 million years to about 2.6 million years. And what's really important to understand about these sediments, and this is both an advantage and a disadvantage is that they are not continuous across time, but instead are exposed in fault blocks, adjacent fault blocks which means that each block of sediment is a unified slice of time separated from another block next to it which has itself a unified period of time with slight gaps in between them. Disadvantaged because we can't trace evolutionary events continuously but advantage because fossils that come, demonstrably come, from particular fault blocks can be narrowed to a very narrow range of environments and associations with other animal species, etc. So, a plus and a minus. And here is the Ledi-Geraru area. Kaye and her team have been working her for more than a decade before they found their first hominid. Looking at the fauna, looking at the geology, trying to understand the environments. And by the way, this is an area called the Lee Adoyta basin and you can see here, here's one fault block, here's another fault block, and here's a third fault block. They're about three or four fault blocks just exposed in this one view, very clearly delineated. You can see one of the faults running right through here. Now, back in 2013, Kaye and her group of paleontologists were surveying an area in the Lee Adoyta basin called the Gurumaha block just in the one fault block. And at the base of this one hillside, there's a volcanic ash that is now well-dated, very precisely dated to 2.8 to 2, plus or minus a handful of years, in the million year range. And on one winter's day, one of our graduate students at ASU, Chalachew Seyoum, was surveying up on this hillside and found this little jaw. That jaw eroded out of this hill, perhaps in a recent rain storm and resides about 10, maybe 12 meters above that volcanic ash. And on the hillside, there are no sediments up above younger that the jaw could have floated down from. It eroded out of that hillside and it's around 10 meters above the tough. So here's the jaw after it has been cleaned up. And I'm here to tell you that it answers some questions, answer some very specific questions. It doesn't answer all the questions. But there's a myth out here in Paleoanthropology that unless you have a complete skeleton, you're not prepared to answer any meaningful questions and I wish to dispel that myth. You know, since Raymond Dart named Australopithecus in 1925, there have been a plethora of hominid species named, recognized; Australopithecus africanus, Paranthropus robustus, Paranthropus boisei, Homo Habilis, on and on. Many of them, if not most of them on the basis of material that we here today would consider, at best, imperfect. A fragment of a jaw, a bit of a brain case, some teeth, and the fact of the matter is is that in the intervening years, the vast majority of those species recognized on the basis of imperfect material have been verified as to be meaningful evolutionary units. We are not at sea when we have small fragments. We are limited in the type of questions we can ask. If complete skeletons were the answer to all of our questions, then Lucy would have settled, once and for all, the debate about when early humans made a commitment to terrestrial bipedality. Instead, she generated what is now going on to five decades of debate about that question. It depends on the question and this question, the question that we address to this jaw, is it the same thing as Australopithecus at 2.8 million or is it something different? And I engaged in that question with my former PhD student, Brian Brian Villmoar now at University of Nevada, Las Vegas, and Chalachew Seyoum our graduate student who found the jaw. And we came to the conclusion that in many respects, it differs from your standard issue generalized Australopithecus jaw. Seen here on the left is a nice jaw of Lucy's species, Australopithecus afarensis and on the right is a reconstructed from a scan of the specimen from Ledi-Geraru. We noticed that the jaw differs rather...these two jaws differ rather remarkably. The afarensis jaw is typically long and narrow with fat molar teeth, primitive pre-molars and so forth. And our major comparison was to something like this, one of the jaws from the Dmanisi site dated to about 1.8 million years which is attributed to Homo erectus. And there's a much greater similarity in the shape of the dental arch, in the form of the teeth, the pre-molars being symmetrical and so forth, to this 1.8 million year old Homo erectus jaw than to Lucy's species. And it extends also to the architecture of the jaw and I'm not going to go into the details here, but underneath the pre-molar, the afarensis jaw is characterized by a highly sculpted out, contour like a chimpanzee probably do, to the very large canine teeth absent in the Ledi-Geraru jaw. The back part of the mandible where the vertical part called the ascending ramus arises from the body of the jaw is located in the Ledi jaw well back of the third molar, not forward as it is in Lucy's species over the second molar. And the upper and lower boundaries of the mandibular borders beneath the teeth and at the base are more or less parallel. And in Australopithecus, they're not, it gets shallower to the rear. And by the way, it's also true of Australopithecus africanus which is slightly closer in age to the Ledi jaw in South Africa, the same kind of thing. So, when we made the comparison to jaws of the genus Homo, later in time obviously because we don't have much in the 2.5 to 3 million year period, the similarities were very apparent to us. This is a jaw that exhibits characteristics that forecast anatomy that is common, the most common anatomical patterns in jaws of the genus Homo younger than 2 million. So we published it, in not quite a year ago, in the Journal of Science as a 2.8 million year old jaw of the genus Homo. Now does it answer questions about what were the adaptive packages present early on in the lineage leading to us? Of course. But what it does do is that it puts one data point in an area that is otherwise a void in the evolution of our own genus. Question is what kind of environment did it live in? Did it live in a dry environment? Did it live in an open one? Germane to the questions about what drove early evolution of Homo. And data that's been put together by Kaye Reed and given to me for this purpose shows that this jaw is found in a context of animal species that lived in essentially grassland environments, very different in terms of how open or closed the habitats were compared to time periods in which Lucy's species lived. And this is just a couple hundred thousand years later. Now, I hasten to add here, I am not asserting that the origin of the genus Homo is due to a drying out of the environment. But one thing we can say, because of the very confined time period of the Gurumaha fault block in which the mandible and the fauna on which this inference is made, suggest that the modal environmental signal at 2.8 in this area is one essentially of a grassland environment. And we can see that by looking at some of the other animal fossils that have been found associated with the horizon from which that mandible has come. This is the Gurumaha block, these are El Salafin bovid frequencies and the horse frequencies, both of which of course are well-known grazers. And together, in the Gurumaha block, they constitute nearly 40% of the macrofauna, excludes elephants and hippos and stuff. I'm not saying it's dry, we're saying it's open. So it's 40% of the macrofauna and that is very impressive compared to the frequencies back in Lucy's time starting just 200,000 years earlier. Opens up areas for inquiry. And finally, some new data coming out of Kenya from Sonia Harmand's group suggests that stone tool use, in fact, began not with the genus Homo, maybe. But perhaps as long ago as 3.5 million years when we have Australopithecus. And if these finds are verified, it opens up a whole new range of possibilities looking at the adaptive packages that constitute the ancestral platform from which the genus Homo emerged. And so to finish up, here we have Ledi-Geraru, here we have our formerly first appearance, a former first appearance of stone tools now pushed back here perhaps and does that imply that the genus Homo itself has even an earlier origin than we think of at 2.8, perhaps back as far as Lucy? Or could Lucy herself have been the first stone tool maker? Thank you. ♪ [music] ♪ - [Philip] We've heard a lot at this point about the evolution of hominids in Africa. It's a complicated history for sure. Let me at this point just cut to the chase and say that humans moved out of Africa probably just after 2 million years ago and it will be that part of the record that I want to emphasize this afternoon. The site of Dmanisi in the Georgian Caucasus is very important, records the oldest known, at this point, the oldest known occupations of Eurasia beginning before 1.85 million years ago. We don't actually have human remains that are that old, but certainly there are stone tools approaching that date. The good part about Dmanisi is that in fact we have not just scraps of headlamp and bumper and so forth, but virtually whole skeletons and a number of them. Now we have five skulls in various states of repair or disrepair. Along with them, there are post cranial bones associated with one juvenile individual particularly perhaps but not clearly associated with one of the adults. Also the material is extremely well-preserved. We're very fortunate in that respect. Along with the humans, of course there are animal bones and many, many of them and there is a very complete lithic record to go along with this material which is well-preserved, as I say, in a very carefully studied stratigraphic context. Several of the specimens from Dmanisi have been in the past likened to African Homo erectus but the skeletons are quite primitive. One of them in particular is strikingly so, Skull 5 which I will talk about. At the moment, I think it's fair to say that the taxidermic identity and the paleobiological significance of the Dmanisi materials remain controversial. Certainly there have been plenty of suggestions and I'm afraid I've been responsible for some of them but we'll see where things go. Dmanisi is situated in Georgia. Georgia is stuck there between the Black Sea and the Caspian with Azerbaijan off to the east. From Tbilisi, the capital, it's about an hour and a half, an hour and 45 minutes ride. Roads are pretty good these days. Roads were terrible 15 years ago. Things have improved. Down to the site, Dmanisi is just a few kilometers from the Armenian border. This is the obligatory excavations in progress slide. There are about four meters of sedimentary deposits at Dmanisi. Much of this stuff is volcanic in origin, it's very ashy. There are some other sediments and silts, but ash is always a primary component which is a good thing. The stratigraphy is complex, all of the sediments are piled atop the Mashavera basalt which is about 1.85 million years old, that's the bottom of the site, the earliest record, 1.85 million years is the date obtained from radiometric methodology. It is secure. The stratigraphy at the site is complex partially because there are a number of piping features. Water was present near the site during periods of heavy rain and so on. Pipes formed underground and then progressed through breaching to collapse towards the surface filled with sediments then got buried again. So it's been a mess, it's been very hard to sort it out. Our geologist, Reid Ferring, has done a huge amount of work in this respect, huge in the Trumpian since. But there have been problems. The first traces of human material were found at Dmanisi in 1991. Excavations in fact have been underway at the site for quite a period of time before that. The site is underneath an old medieval town that was on the Silk Road. The archeologists were busy at Dmanisi for some time poking around the foundations of the old buildings and eventually they began to dig up stuff that didn't seem to belong there, not just the goats and fish bones from medieval suppers, but things that looked quite antique indeed. The paleontologists came in and ascertain that yes, the material was ancient, deeper excavations got underway and in 1991, the folks at Dmanisis were rewarded with this jaw, the D211 mandible. It's remarkably complete, not all of it is there. But what there is remarkably well-preserved. It's a small jaw and in a number of respects, it does look like Homo erectus. You've seen one reference to this specimen already. The teeth are about right for Homo erectus as are the proportions of the mandible itself. The cranium which turns out to be the match to the little mandible was found later in 1999, D2282 is a small cranium, very small capacity, surprisingly so for Homo erectus. Only a bit more than 650 CCs in this case. Despite the small brain, the thing does share a number of characteristics with particularly early African erectus. This hulk turned up at the site in 2005. It's way down at the bottom of the site and within a few days after the fossil had been uncovered and cleaning was underway prior to trying to lift it out, there was a very heavy rain. Things were very nearly washed out. Of course we have a cover over the site, there is protection, but it rained so much and so long that water began to trickle in around the sides of the excavations and things were dicey for a while. Fortunately, D4500 survived. There it is all cleaned up. It turns out that the cranium found in 2005 is a perfect match, once again, to a mandible, D2600, which had been found earlier in the year 2000. The upper and the lower, the cranium and the mandible simply clicked together once the stuff have been cleaned off, there was no doubt at all. There is some pathology on the mandible that matches, comparable pathology in the region of the ear of the cranium so there is no doubt about the match. More than other Dmanisi hominins, Skull 5, as this one is known, exhibits very robust morphology. It's pretty clearly a male individual. Determining sex in the case of these fossil hominins is often tricky, often can't be done very accurately. But in this case, we think we have a match, the skull says male all over. Such a pattern given the fact that it has the smallest brain of all the Dmanisi hominins because it is unexpected. Normally for other primates, humans too of course, but for primates, higher primates generally, males tend to exceed the females in brain size by something like 8 to 10 to 15%. So, having the tiniest brain attached to the most robust cranium and jaw is a bit surprising. You can see that there is a good deal of variation within the Dmanisi assemblage. The little jaw goes with a smallish brain case which is quite gracile in its construction. We peg that one Skull 2 as likely a female. Skull 5, on the other hand is much more robust, clearly distinctive in a number of respects. Number 1 is like Homo erectus, number 4 is a small individual. That one seems to have lived to a ripe old age since it had lost almost its entire dentition, maybe one tooth was still in place at the time the individual died. That one may or may not be male, we're not sure. Anyway, there is a great deal of diversity at Dmanisi. The crania do look different. This raises the question of "How many species might be documented at the site?" This is a question that's been plaguing us for some time. I think myself on the basis of the shared anatomy among the Dmanisi individuals, they have a common bow plan extending not just to the cranial vault but to the face insofar as we have it represented. And also to the details of the cranial base suggest, the common bow plan suggests that all of the individuals are drawn from just one group. We've done extensive resampling analysis as well which cause us to come to the same conclusion that really, in fact, the skulls, the post-cranial remains that go with them, are drawn from just one population. Now there is stratigraphic evidence relating to this question. It doesn't solve the question of course, but it's important information. It's good to know that the material was all washed into these deposits or arrived in the site by one means or another at about the same time that is the duration here can't be more than a few hundred or perhaps a thousand years or so according to the best analyses conducted by the geological side of the team. We'll say, then, that it's very likely that the Dmanisi assemblage samples a population belonging to a single species. I know there may be objections to this. I'm sure there will be, there have been in the past. If it's true, then such a situation is quite rare. Of course, at most localities where hominins are discovered, you've heard a lot about East Africa at this point, Koobi Fora, Olduvai. Also at Sangiran in Java where there are a number of fossils. The material is scattered through a very long sequence of deposits covering a long period in time. Time as a contributor variation just cannot be discounted. If the Dmanisi fossils document what we can call a population in the past extending over quite a number of years of course, then the next question, the next important question is how the Dmanisi sample may relate to the hominin taxa that have previously been recognized. Skill 5 of course has a very small brain case, a very large projecting face in the vault. Also in the basal cranium, there are some resemblances, not a lot, but some resemblances to Homo erectus. Skull 3 which I have not shown you a picture of before is the sub-adult from Dmanisi. Skull 3 is pictured here down below. Skull 3 is similar to Homo habilis. This is true for the bow ridge, the extended brow ridge development. It's true particularly for the shape of the vault, the rounding at the back and for the mid-facial profile. Skull 3, I must point out, is sub-adult so we must allow for some extra growth to have occurred if the individual had grown up. It might have looked, had it grown up, a bit more robust and a bit like the skull to the left there, Homo habilis KNM-ER 1813. Skulls 2 and 4 also have their peculiar aspects, of course. They have a number of primitive characters that they also share some features with Homo habilis. So, which species? There is, as I've pointed out, much variation within the Dmanisi paleodeme. This is not an easy question, the question as to which species may be represented. Skull 5, the very small brained and very robust and very primitive looking individual does indeed share some characters with Australopithecus as well as Homo. So perhaps in this case, the line, the division between Australopithecus on the one hand and earlier Homo on the other is not so clear cut after all. Many of these shared similarities are primitive characters and unfortunately they don't help us much in answering key questions about phylogenetic affinities. Other characters expressed in the Dmanisi materials are Homo erectus-like and pretty clearly they are specialized characters, characters that have changed during the course of evolution, characters that are said to be derived. These characters include the form of the brow ridge for example which is larger and bar-like, a little bit of midline, keeling on the vault, details of temporal bone construction, things of that sort on the underside of the vault. Indeed, when Skulls 1 and 2 were first described back in the year 2000, they were grouped with early Homo erectus from the Turkana basin. If the fossils are included with Homo erectus, clearly that's one way to deal with the material is simply to lump it with Homo erectus. If that is the course we take, then it must be recognized that the boundaries between Homo erectus on the one hand and other early Homo taxa will become less distinct. It will be particularly difficult to distinguish early Homo erectus, African Homo erectus from specimens attributed to earlier Homo to Homo habilis in particular. Homo habilis is considered apart from Homo rudolfensis. So, to sum up at this point, here is again a speciose view of Hominin phylogeny done by Bernard Wood with Meave Leakey several years ago. You can read the caution sign. To sum up then, there is apparently no simple answer to the question as to which species may be represented at our site. Indeed this question is often a tricky one. It's been a hard one for paleoanthropologists to deal with for a long time. In one view, this view expressed on the slide, Dr. Wood showed you another version of this very spaciose hominin phylogeny. In that view hominin evolution has produced a veritable flowering of lineages over more than 6 million years. Such bushiness, as it were, is particular evident for the 2.5 to 1 million year ago interval. This interval in which Paranthropus on the one hand, Australopithecus and Homo are represented by multiple species for each group. At Dmanisi the fossils seem clearly to be Homo. Now there are some points of overlap with Australopithecus as I pointed out, but I would say unbalanced the evidence favors grouping all of our fossils with the genus Homo, very little doubt about that. At the same time, the assemblage at Dmanisi does not fall neatly into one of the taxonomic packages that have been proposed: Homo habilis, Homo rudolfensis, Homo ergaster, Homo erectus and so on. If I were pressed and I do feel pressed at this point, given the morphological resemblances of Dmanisi to both Homo habilis in a very strict sense, just those fossils allocated to Homo habilis, not to Homo rudolfensis. Given the resemblances of our material to Homo habilis, and to early Homo erectus, particularly African Homo erectus, I would probably argue, I will argue, that it is most reasonable to place all of these fossils within a single evolutionary species. I would say that the Dmanisi fossils constitute just one population within this unbranched lineage. Now, this is not to raise the specter of just one species at a time, or to suggest that there isn't a great deal of diversity in the hominin record, clearly there was particularly in that interval after, about 2.5 million years. But as far as our evidence is concerned, it seems to me the best way to go, simply to place all the fossils within one evolutionary species. Then of course we'd have to argue about what to call it, but this is not the place for that. So, with that, thanks for listening. Thanks very much. ♪ [music] ♪ - [Pascal] Thanks very much for this great afternoon, to all the speakers. I'm especially grateful to Dan Lieberman for having set the stage with a lot of carnage and meat-eating, because the molecules I talk about today have to do with vertebrates and what we eat and what happens to it in our bodies. So this afternoon I'd like to share an idea about a way that a molecule could be driving speciation and share some evidence for it in Vigo [sp], not in primates but in mice. I like to start with by acknowledging the people who've done some of the heavy lifting, including Fang Ma who's back in Chengdu, a former lab member and Darius Ghaderi and my team here especially Stevan Springer and Miriam Cohen, as well as my collaborators, Ajit Varki and his team. The kelp there in the background is actually an analogy I use when I talk about the glycocalyx. Every living life, every living cell has a sugar coat called glycocalyx which consist of glycolipids and glycoprotiens that completely cover the cell and give it its molecular identity. These molecules swing around very much like the kelp in the ocean right here. And if we make ourselves hundreds of millions of times smaller and land on a cell, one of my favorite cells, a mammalian sperm cell, we would see something that reminds us of one of these kelp forests. These are the glycolipids and glycoproteins. All of them share short sugar chains on them, each little sugar is about one nanometer big. And what they share is that most of these chains terminate in a sugar coat sialic acid that helps define the identity of the cell type and it tells the body that this is a self cell. So sialic acid can be thought of as a very potent self signal. You can visualize them here with an antibody and you see the entire surface of the sperm, it's payload so to speak is the haploid genome in blue. And the surface of the sperm is completely covered in sialic acid. To go back to the kelp analogy, macrocystis kelp has these big terminal bulbs that help it float and it defines the outer edge, the molecular frontier of every cell, that's what you can think of as sialic acids. They're very important because they're telling the body that this is self and they play a role in fertilization, in gestation, in development including during pregnancy. Peter Medawar many years ago coined the phrase "immunological paradox of mammalian pregnancy" where a female, a mother, is gestating an individual that is genetically not identical to her within her body, in a very intimate contact. The interface between the fetal cells of the trophoblast and the mother includes these sialic acids, these sugar molecules found on cell surfaces of all vertebrates. This matters, it can be quite dramatic. This young fellow here was born in 1963 and he had a problem; his mother was type O, had a lot of antibodies against type A blood. And they had a former son and his father was type A. So what happened during the pregnancy is that the antibodies that his mother were making passed through the placenta and almost killed him. He was born with massive hemolytic disease of the newborn that had only been described a couple of years earlier. And it's only because he was given two complete blood transfusions that he can stand here today and give a talk. So sugars and mismatches of sugars are really important. But I would like to propose that there is another immunological paradox and it's the one about mammalian fertilization. How do sperm manage to survive this journey from insemination to the place of fertilization way up in the ampulla of the oviduct? If you think back, when you were a sperm, the reproductive tract of your mother was about the equivalent of six kilometers, we're back to running. Of course, hundreds of millions of potential you's were inseminated, but only one made it up all the way to the ampulla. And that is partly due to a massive influx of immune cells of the mother upon insemination that take out and actively kill, potentially select, most of the sperm. Only a few hundreds make it to the oviduct where they capacitate, they start sprinting, galloping and one of them meets the egg and fertilizes it. So, females may be scrutinizing and even selecting sperm. Why would they do that? Well, one thing they might have to look out for is, is it the correct species? Male mammals are quite famous for trying to mate with anything that is shaped roughly like that. But the female might be interested in some read out of the fitness of the male who made the sperm or in the fact that the male is genetically compatible also more importantly that the sperm is still functional. Wasting one precious egg on a sperm that already lost its acrosome and is not fit to make a surviving embryo would be a terrible waste. So, I come back to the sialic acid on the surface of cells and in most mammals, the two most common sialic acids are called N-acetylneuraminic acid and N-glycolylneuraminic acid, AC and GC for short. What is interesting is that there's an enzyme the modifies AC to GC and humans are natural knock outs. This is work by Ajit Varki's laboratory that over the last 15 years has found the mechanism. We are knock out for a gene that was an insertion of a selfish piece of DNA that destroyed the gene. We cannot make the GC anymore. All of us in this room are pure AC on our cell surfaces. So the cell surface of a human differs dramatically from that of most other mammals. So with all our close living ape relatives, we share AC. But because of a mutation that is quite well-timed with three different methods using coalescence, molecular clock and the type of element that is present, we know that this mutation happened between 2 and 3 million years ago. And we know that it causes us to only have one type of sugar on our cell surface, of sialic acid. Now you'd think it's a tiny, tiny change in DNA, why could this be a big deal? I haven't mentioned that your average cell has tens to hundreds of millions of this molecule. So a tiny change in your DNA changes the flavor, the molecular flavor of your cells in a big way. A human cell would appear in one flavor and a non-human cell in a completely different flavor. What could have driven this? You're looking at a model of a cell surface of a red blood cell which make up over 80% of all your cells. And they're targeted by some of the most important pathogens that we know for human kind such as falciparum, malaria. This molecule encircled is glycophorin A that carries a lot of sialic acid which malaria uses to get into the host. So a couple of years back with Ajit, we commented on the fact that it is known that the apes that still make most of our great ape cousins sick, they use sialic acid that we don't have anymore. They cannot infect us. So, one possible driving force for the loss of this sugar initially might have been to escape a pathogen such as an ancestral malaria. We got a nice break. Unfortunately, much, much later in the Neolithic with agriculture and the expansion of Anopheles mosquito species, malaria caught up with us with a vengeance and is now highly specific for the sugar we have on human cells. Now, interestingly, as we've heard somewhere along the line to Homo, we became top predators and we regularly engage in hunting or scavenging or a combination of both. And when you eat this non-human sugar, you actually incorporate it and you start making an immune reaction to it. So after having lost the sugar, we started getting regularly immunized to it and making antibodies. And there is ongoing work showing that this is incorporated, is relevant for modern Homo sapiens, all of us who eat red meat which is the biggest source of this non-human sugar, continue to immunize ourselves and to incorporate it. So several years back, we asked, "Well, could it be that if sperm differs so dramatically that a change in cell surface sugars could actually have been involved in this reproductive incompatibility that I was unlucky enough to suffer from when I was born? That was ABO blood groups, very unusual, a rare case. But this would have been a very powerful point, a way to immunize the mother against the sugar she doesn't have. Could this have been involved, this mutation? The fixation of it, could that have been driven? Could that have driven the speciation along the lineage to modern Homo? So one thing we could do at the time is obtain chimpanzee sperm in a non-invasive fashion. I shall not go into details. And expose those chimpanzee sperm to human serum with antibodies and show that they die. But the reverse is not true. We could also show that compliment gets deposited on sperm. It seems to be an antibody-driven killing mechanism in human serum. Luckily by then, there was a model mouse that carried the same mutation that we humans carry. You can see that the wild-type mouse has the non-human sialic acid on its sperm, the knock out mouse doesn't. And so we said, "Well, let's use these mice to prove whether this mechanism could function." And we could show that yes, the immunized mice would make antibodies that stick to the sperm. The two groups of females, we mated with different males, had similar comparable levels. And there were antibodies very importantly in the female reproductive tract of these mice. So, that would be a way to model female immunity being hostile to the ancestral molecule. And after hundreds of mating experiments, effectively the only group of pairings where there was a 30% reduction in fertility was with females lacking a sugar, making antibodies against a sugar that was on sperm that was mismatched. Now, 30% reduction in fertility, is that important? Could that drive speciation? And this is where Stevan Springer came in and came up with an instantaneous model of selection with pay-off matrices of all possible combination between the genotypes of males and females. Interestingly, this process could not start by sexual selection. This is a type of sexual selection, female immunity, punishing sperm for carrying the wrong sugar. But if a pathogen were to introduce and favor the mutation, very quickly as the frequency of the mutation rises in the females, males get rewarded by also losing the sugar because they gain compatibility. And after a certain moment, you can cross a threshold from negative selection in females, in pink, to a net positive selection in black. In males, as soon as there is enough females that lack the sugar, it is worth losing the sugar. So that should gain compatibility. We modeled the effect of both the degree of incompatibility and promiscuity and it showed that with a promiscuity of about three matings per ovulation. So a female would have to mate between two and five males for each egg. And a frequency of only about 0.4% which is 1 in 25 females will be homozygous. This process would become a directional selection fixing the allele. So in a cartoon version, the idea is that pathogens are prominently driving the sugars on your cell surfaces, that's why we have blood groups. But usually these changes go back and forth. And they generate selection that oscillates and results in polymorphisms that do not fix. But if this process comes on the sexual selection via female antibodies against molecules on the sperm, you have directional selection that rapidly fixes the loss of functional mutation. So what we propose might have happened somewhere in the past and possibly at the beginning of the genus Homo is a very important pathogen driving changes in the glycocalyx of the host. Some of the hosts would have been homozygous. They would have looked very different. The females by virtue of their new mode of life with much hunting and contact with other animal products would have been immunized against this sugar. That immunity also protected them from infection from these bugs, but it would preclude optimal compatibility with males that still had the ancestral molecule, eventually driving apart two populations even within the same sympatric environment. So as a model for sympatric speciation of ancestral hominids. The hope now is to get fossil material to actually look for incorporated monosaccharides as far back as 3 or 4 million years and find out which lineages still have both sugars as opposed to which lineages already had just one sugar and would make a better candidate for our ancestors. Thank you very much. .♪ [music] ♪

Contents

Names and taxonomy

Evolutionary tree chart emphasizing the subfamily Homininae and the tribe Hominini. After diverging from the line to Ponginae the early Homininae split into the tribes Hominini and Gorillini. The early Hominini split further, separating the line to Homo from the lineage of Pan. Currently, tribe Hominini designates the subtribes Hominina, containing genus Homo; Panina, genus Pan; and Australopithecina, with several extinct genera—the subtribes are not labelled on this chart.
Evolutionary tree chart emphasizing the subfamily Homininae and the tribe Hominini. After diverging from the line to Ponginae the early Homininae split into the tribes Hominini and Gorillini. The early Hominini split further, separating the line to Homo from the lineage of Pan. Currently, tribe Hominini designates the subtribes Hominina, containing genus Homo; Panina, genus Pan; and Australopithecina, with several extinct genera—the subtribes are not labelled on this chart.

See Hominidae for an overview of taxonomy.

The Latin noun homō (genitive hominis) means "human being" or "man" in the generic sense of "human being, mankind".[6] The binomial name Homo sapiens was coined by Carl Linnaeus (1758).[7] Names for other species of the genus were introduced beginning in the second half of the 19th century (H. neanderthalensis 1864, H. erectus 1892).

Even today, the genus Homo has not been properly defined.[8][9][10] Since the early human fossil record began to slowly emerge from the earth, the boundaries and definitions of the genus Homo have been poorly defined and constantly in flux. Because there was no reason to think it would ever have any additional members, Carl Linnaeus did not even bother to define Homo when he first created it for humans in the 18th century. The discovery of Neanderthal brought the first addition.

 A model of the evolution of the genus Homo over the last 2 million years (vertical axis). The rapid "Out of Africa" expansion of H. sapiens is indicated at the top of the diagram, with admixture indicated with Neanderthals, Denisovans, and unspecified archaic African hominins.[11]
A model of the evolution of the genus Homo over the last 2 million years (vertical axis). The rapid "Out of Africa" expansion of H. sapiens is indicated at the top of the diagram, with admixture indicated with Neanderthals, Denisovans, and unspecified archaic African hominins.[11]

The genus Homo was given its taxonomic name to suggest that its member species can be classified as human. And, over the decades of the 20th century, fossil finds of pre-human and early human species from late Miocene and early Pliocene times produced a rich mix for debating classifications. There is continuing debate on delineating Homo from Australopithecus—or, indeed, delineating Homo from Pan, as one body of scientists argue that the two species of chimpanzee should be classed with genus Homo rather than Pan. Even so, classifying the fossils of Homo coincides with evidences of: 1) competent human bipedalism in Homo habilis inherited from the earlier Australopithecus of more than four million years ago, (see Laetoli); and 2) human tool culture having begun by 2.5 million years ago.

From the late-19th to mid-20th century, a number of new taxonomic names including new generic names were proposed for early human fossils; most have since been merged with Homo in recognition that Homo erectus was a single and singular species with a large geographic spread of early migrations. Many such names are now dubbed as "synonyms" with Homo, including Pithecanthropus,[12] Protanthropus,[13] Sinanthropus,[14] Cyphanthropus,[15] Africanthropus,[16] Telanthropus,[17] Atlanthropus,[18] and Tchadanthropus.[19]

Classifying the genus Homo into species and subspecies is subject to incomplete information and remains poorly done. This has led to using common names ("Neanderthal" and "Denisovan") in even scientific papers to avoid trinomial names or the ambiguity of classifying groups as incertae sedis (uncertain placement)—for example, H. neanderthalensis vs. H. sapiens neanderthalensis, or H. georgicus vs. H. erectus georgicus.[20] Some recently extinct species in the genus Homo are only recently discovered and do not as yet have consensus binomial names (see Denisova hominin and Red Deer Cave people).

John Edward Gray (1825) was an early advocate of classifying taxa by designating tribes and families.[21] Wood and Richmond (2000) proposed that Hominini ("hominins") be designated as a tribe that comprised all species of early humans and pre-humans ancestral to humans back to after the chimpanzee-human last common ancestor; and that Hominina be designated a subtribe of Hominini to include only the genus Homo—that is, not including the earlier upright walking hominins of the Pliocene such as Australopithecus, Orrorin tugenensis, Ardipithecus, or Sahelanthropus.[22] Designations alternative to Hominina existed, or were offered: Australopithecinae (Gregory & Hellman 1939) and Preanthropinae (Cela-Conde & Altaba 2002);[23][24][25] and later, Cela-Conde and Ayala (2003) proposed that the four genera Australopithecus, Ardipithecus, Praeanthropus, and Sahelanthropus be grouped with Homo within Hominina.[26]

Evolution

Several species, including Australopithecus garhi, Australopithecus sediba, Australopithecus africanus, and Australopithecus afarensis, have been proposed as the direct ancestor of the Homo lineage.[27][28] These species have morphological features that align them with Homo, but there is no consensus as to which gave rise to Homo. The advent of Homo was traditionally taken to coincide with the first use of stone tools (the Oldowan industry), and thus by definition with the beginning of the Lower Palaeolithic.[29] The emergence of Homo also coincides roughly with the onset of Quaternary glaciation, the beginning of the current ice age.

A fossil mandible fragment dated to 2.8 million years ago which may represent an intermediate stage between Australopithecus and Homo was discovered in 2015 in Afar, Ethiopia (LD 350-1).[30] Some authors would push the development of Homo past 3 Mya, by including Kenyanthropus (a fossil dated 3.2 to 3.5 Mya, usually classified as an australopithecine species) into the genus Homo.[31]

The most salient physiological development between the earlier australopithecine species and Homo is the increase in cranial capacity, from about 450 cm3 (27 cu in) in A. garhi to 600 cm3 (37 cu in) in H. habilis. Within the genus Homo, cranial capacity again doubled from H. habilis through Homo ergaster or H. erectus to Homo heidelbergensis by 0.6 million years ago. The cranial capacity of H. heidelbergensis overlaps with the range found in modern humans.

Homo erectus has often been assumed to have developed anagenetically from Homo habilis from about 2 million years ago. This scenario was strengthened with the discovery of Homo erectus georgicus, early specimens of H. erectus found in the Caucasus, which seemed to exhibit transitional traits with H. habilis. As the earliest evidence for H. erectus was found outside of Africa, it was considered plausible that H. erectus developed in Eurasia and then migrated back to Africa. Based on fossils from the Koobi Fora Formation, east of Lake Turkana in Kenya, Spoor et al. (2007) argued that H. habilis may have survived beyond the emergence of H. erectus, so that the evolution of H. erectus would not have been anagenetically, and H. erectus would have existed alongside H. habilis for about half a million years (1.9 to 1.4 million years ago), during the early Calabrian.[32]

Migration

Some of H. ergaster migrated to Asia, where they are named Homo erectus, and to Europe with Homo georgicus. H. ergaster in Africa and H. erectus in Eurasia evolved separately for almost two million years and presumably separated into two different species.

Homo rhodesiensis, who were descended from H. ergaster, migrated from Africa to Europe and became Homo heidelbergensis and later (about 250,000 years ago) Homo neanderthalensis and the Denisova hominin in Asia. The first Homo sapiens, descendants of H. rhodesiensis, appeared in Africa about 250,000 years ago. About 100,000 years ago, some H. sapiens sapiens migrated from Africa to the Levant and met with resident Neanderthals, with some admixture.[33] Later, about 70,000 years ago, perhaps after the Toba catastrophe, a small group left the Levant to populate Eurasia, Australia and later the Americas. A subgroup among them met the Denisovans[34] and, after further admixture, migrated to populate Melanesia. In this scenario, non-African people living today are mostly of African origin ("Out of Africa model"). However, there was also some admixture with Neanderthals and Denisovans, who had evolved locally (the "multiregional hypothesis"). Recent genomic results from the group of Svante Pääbo also show that 30,000 years ago at least three major subspecies coexisted: Denisovans, Neanderthals and anatomically modern humans.[35] Today, only H. sapiens remains, with no other extant species.

List of species

The species status of H. rudolfensis, H. ergaster, H. georgicus, H. antecessor, H. cepranensis, H. rhodesiensis, H. neanderthalensis, Denisova hominin, Red Deer Cave people, and H. floresiensis remains under debate. H. heidelbergensis and H. neanderthalensis are closely related to each other and have been considered to be subspecies of H. sapiens. Recently, nuclear DNA from a Neanderthal specimen from Vindija Cave has been sequenced using two different methods that yield similar results regarding Neanderthal and H. sapiens lineages, with both analyses suggesting a date for the split between 460,000 and 700,000 years ago, though a population split of around 370,000 years is inferred. The nuclear DNA results indicate about 30% of derived alleles in H. sapiens are also in the Neanderthal lineage. This high frequency may suggest some gene flow between ancestral human and Neanderthal populations due to mating between the two.[36]

Homo naledi was discovered near Johannesburg, South Africa in 2013 and announced on 10 September 2015. Fossils indicate the hominid was 1.45-1.5 meters tall and had a small brain.[37] The fossils have yet to be dated.[38]

Comparative table of Homo species
Species Temporal range kya Habitat Adult height Adult mass Cranial capacity (cm³) Fossil record Discovery / publication of name
H. habilis 2,100 – 1,500[39] Africa 110-140 cm (4 ft 11 in) 33–55 kg (73–121 lb) 510–660 Many 1960/1964
H. erectus 1,900 – 70

[40]

Africa, Eurasia (Java, China, India, Caucasus) 180 cm (5 ft 11 in) 60 kg (130 lb) 850 (early) – 1,100 (late) Many[41] 1891/1892
H. rudolfensis
membership in Homo uncertain
1,900 Kenya 700 2 sites 1972/1986
H. gautengensis
also classified as H. habilis
1,900 – 600 South Africa 100 cm (3 ft 3 in) 3 individuals[42] 2010/2010
H. ergaster
also classified as H. erectus
1,800 – 1,300[43] Eastern and Southern Africa 700–850 Many 1975
H. antecessor
also classified as H. heidelbergensis
1,200 – 800 Spain 175 cm (5 ft 9 in) 90 kg (200 lb) 1,000 2 sites 1997
H. cepranensis
a single fossil, possibly H. erectus
900 – 350 Italy 1,000 1 skull cap 1994/2003
H. heidelbergensis 600 – 350[44] Europe, Africa, China 180 cm (5 ft 11 in) 90 kg (200 lb) 1,100–1,400 Many 1908
H. neanderthalensis
possibly a subspecies of H. sapiens
350 – 40[45] Europe, Western Asia 170 cm (5 ft 7 in) 55–70 kg (121–154 lb) (heavily built) 1,200–1,900 Many (1829)/1864
H. naledi
Undetermined South Africa 150 centimetres (4 ft 11 in) tall 45 kilograms (99 lb) 450 15 individuals 2013/2015
H. tsaichangensis
possibly H. erectus
190 – 10[46] Taiwan 1 individual pre-2008/2015
H. rhodesiensis
also classified as H. heidelbergensis
300 – 120 Zambia 1,300 Very few 1921
H. sapiens
(modern humans)
200[47]

 – present

Worldwide 150 - 190 cm (4 ft 7 in - 6 ft 3 in) 50–100 kg (110–220 lb) 950–1,800 (extant) —/1758
H. floresiensis
classification uncertain
190 – 50 Indonesia 100 cm (3 ft 3 in) 25 kg (55 lb) 400 7 individuals 2003/2004
Denisova hominin
possible H. sapiens subspecies or hybrid
40 Russia 1 site 2000/2010
Red Deer Cave people
possible H. sapiens subspecies or hybrid
14.5–11.5 China Very few 2012

See also

References

  1. ^ The conventional estimate on the age of H. habilis is at roughly 2.1 to 2.3 million years. Stringer, C.B. (1994). "Evolution of early humans". In Steve Jones, Robert Martin & David Pilbeam (eds.). The Cambridge Encyclopedia of Human Evolution. Cambridge: Cambridge University Press. p. 242.  McHenry, H.M (2009). "Human Evolution". In Michael Ruse & Joseph Travis. Evolution: The First Four Billion Years. Cambridge, Massachusetts: The Belknap Press of Harvard University Press. p. 265. ISBN 978-0-674-03175-3.  Suggestions for pushing back the age to 2.8 Mya were made in 2015 based on the discovery of a jawbone: Wilford, John Noble (2015-03-04). "Jawbone Fossil Fills a Gap in Early Human Evolution". The New York Times. ISSN 0362-4331. Retrieved 2015-05-30. Spoor, Fred; Gunz, Philipp; Neubauer, Simon; Stelzer, Stefanie; Scott, Nadia; Kwekason, Amandus; Dean, M. Christopher (March 5, 2015). "Reconstructed Homo habilis type OH 7 suggests deep-rooted species diversity in early Homo". Nature. 519 (7541): 83–86. doi:10.1038/nature14224. ISSN 0028-0836. PMID 25739632. . Villmoare, Brian; Kimbel, William H.; Seyoum, Chalachew; Campisano, Christopher J.; DiMaggio, Erin N.; Rowan, John; Braun, David R.; Arrowsmith, J. Ramón; Reed, Kaye E. (2015-03-20). "Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia". Science. 347 (6228): 1352–1355. doi:10.1126/science.aaa1343. ISSN 0036-8075. PMID 25739410. 
  2. ^ Schuster, Angela M. H. (1997). "Earliest Remains of Genus Homo". Archaeology. 50 (1). Retrieved 5 March 2015.  The line to the earliest members of Homo made final separation from the lineage of Pan by late Miocene or early Pliocene times—with date estimates by several specialists ranging from 13 million years ago to more recently than six million years ago.
    • Arnason, U; Gullberg, A; Janke, A (1998). "Molecular timing of primate divergences as estimated by two nonprimate calibration points". J. Mol. Evol. 47 (6): 718–27. doi:10.1007/PL00006431. PMID 9847414. 
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    • Wakeley, J (2008). "Complex speciation of humans and chimpanzees". Nature. 452 (7184): E3–4. doi:10.1038/nature06805. PMID 18337768.  "Patterson et al. suggest that the apparently short divergence time between humans and chimpanzees on the X chromosome is explained by a massive interspecific hybridization event in the ancestry of these two species. However, Patterson et al. do not statistically test their own null model of simple speciation before concluding that speciation was complex, and—even if the null model could be rejected—they do not consider other explanations of a short divergence time on the X chromosome. These include natural selection on the X chromosome in the common ancestor of humans and chimpanzees, changes in the ratio of male-to-female mutation rates over time, and less extreme versions of divergence with gene flow. I therefore believe that their claim of hybridization is unwarranted." see current estimates regarding complex speciation.
  3. ^ [1], BBC
  4. ^ Green, R.E.; Krause, J.; Briggs, A.W.; Maricic, T.; Stenzel, U.; Kircher, M.; Patterson, N.; Li, H.; Zhai, W.; Fritz, M.H.Y.; Hansen, N.F. (2010). "A draft sequence of the Neandertal genome". Science. 328 (5979): 710–722. doi:10.1126/science.1188021. PMID 20448178. 
  5. ^ Lowery, R.K.; Uribe, G.; Jimenez, E.B.; Weiss, M.A.; Herrera, K.J.; Regueiro, M.; Herrera, R.J. (2013). "Neanderthal and Denisova genetic affinities with contemporary humans: Introgression versus common ancestral polymorphisms". Gene. 530 (1): 83–94. doi:10.1016/j.gene.2013.06.005. PMID 23872234.  This study raises the possibility of observed genetic affinities between archaic and modern human populations being mostly due to common ancestral polymorphisms.
  6. ^ The word "human" itself is from Latin humanus, an adjective formed on the root of homo, thought to derive from a Proto-Indo-European word for "earth" reconstructed as *dhǵhem-. dhghem The American Heritage Dictionary of the English Language: Fourth Edition. 2000.
  7. ^ Linné, Carl von (1758). Systema naturæ. Regnum animale. (10 ed.). pp. 18, 20. Retrieved 19 November 2012. . Note: In 1959, Linnaeus was designated as the lectotype for Homo sapiens (Stearn, W. T. 1959. "The background of Linnaeus's contributions to the nomenclature and methods of systematic biology", Systematic Zoology 8 (1): 4-22, p. 4) which means that following the nomenclatural rules, Homo sapiens was validly defined as the animal species to which Linnaeus belonged.
  8. ^ Schwartz, Jeffrey H.; Tattersall, Ian (28 August 2015). "Defining the genus Homo". Science. 349 (6251): 931–932. doi:10.1126/science.aac6182. Retrieved 2015-11-02. 
  9. ^ Lents, Nathan (4 October 2014). "Homo naledi and the Problems with the Homo Genus". The Wildernist. Retrieved 2015-11-02. 
  10. ^ Wood, B.; Collard, M. (2 April 1999). "The human genus". Science. 284 (5411): 65–71. doi:10.1126/science.284.5411.65. PMID 10102822. 
  11. ^ Stringer, C. (2012). "What makes a modern human". Nature. 485 (7396): 33–35. doi:10.1038/485033a. PMID 22552077. 
  12. ^ "ape-man", from Pithecanthropus erectus (Java Man), Eugène Dubois, Pithecanthropus erectus : eine menschenähnliche Übergangsform aus Java (1894), identified with the Pithecanthropus alalus (i.e. "non-speaking ape-man") hypothesized earlier by Ernst Haeckel
  13. ^ "early man", Protanthropus primigenius Ernst Haeckel, Systematische Phylogenie vol. 3 (1895), p. 625
  14. ^ "Sinic man", from Sinanthropus pekinensis (Peking Man), Davidson Black (1927).
  15. ^ "crooked man", from Cyphanthropus rhodesiensis (Rhodesian Man) William Plane Pycraft (1928).
  16. ^ "African man", used by T. F. Dreyer (1935) for the Florisbad Skull he found in 1932 (also Homo florisbadensis or Homo helmei). Also the genus suggested for a number of archaic human skulls found at Lake Eyasi by Weinert (1938). Leaky, Journal of the East Africa Natural History Society' (1942), p. 43.
  17. ^ "remote man"; from Telanthropus capensis (Broom and Robinson 1949), see (1961), p. 487.
  18. ^ from Atlanthropus mauritanicus, name given to the species of fossils (three lower jaw bones and a parietal bone of a skull) discovered in 1954 to 1955 by Camille Arambourg in Tighennif, Algeria. Arambourg, C. (1955). "A recent discovery in human paleontology: Atlanthropus of ternifine (Algeria)". American Journal of Physical Anthropology. 13 (2): 191–201. doi:10.1002/ajpa.1330130203. 
  19. ^ Y. Coppens, "L'Hominien du Tchad", Actes V Congr. PPEC I (1965), 329f.; "Le Tchadanthropus", Anthropologia 70 (1966), 5–16.
  20. ^ Alexandra Vivelo (2013), Characterization of Unique Features of the Denisovan Exome
  21. ^ J. E. Gray, "An outline of an attempt at the disposition of Mammalia into Tribes and Families, with a list of genera apparently appertaining to each Tribe", Annals of Philosophy', new series (1825), pp. 337–344.
  22. ^ Wood and Richmond; Richmond, BG (2000). "Human evolution: taxonomy and paleobiology". Journal of Anatomy. 197 (Pt 1): 19–60. doi:10.1046/j.1469-7580.2000.19710019.x. PMC 1468107Freely accessible. PMID 10999270. 
  23. ^ Brunet, M.; et al. (2002). "A new hominid from the upper Miocene of Chad, central Africa". Nature. 418: 145–151. doi:10.1038/nature00879. PMID 12110880. 
  24. ^ Cela-Conde, C.J.; Ayala, F.J. (2003). "Genera of the human lineage". PNAS. 100 (13): 7684–7689. doi:10.1073/pnas.0832372100. PMC 164648Freely accessible. PMID 12794185. 
  25. ^ Wood, B.; Lonergan, N. (2008). "The hominin fossil record: taxa, grades and clades" (PDF). J. Anat. 212: 354–376. doi:10.1111/j.1469-7580.2008.00871.x. PMC 2409102Freely accessible. PMID 18380861. 
  26. ^ Cela-Conde, C. J.; Ayala, F. J. (2003). "Genera of the human lineage". Proceedings of the National Academy of Sciences. 100 (13): 7684–7689. doi:10.1073/pnas.0832372100. PMC 164648Freely accessible. PMID 12794185. 
  27. ^ Pickering, R.; Dirks, P. H.; Jinnah, Z.; De Ruiter, D. J.; Churchill, S. E.; Herries, A. I.; Berger, L. R. (2011). "Australopithecus sediba at 1.977 Ma and implications for the origins of the genus Homo". Science. 333 (6048): 1421–1423. doi:10.1126/science.1203697. PMID 21903808. 
  28. ^ Asfaw, B.; White, T.; Lovejoy, O.; Latimer, B.; Simpson, S.; Suwa, G. (1999). "Australopithecus garhi: a new species of early hominid from Ethiopia". Science. 284 (5414): 629–635. doi:10.1126/science.284.5414.629. PMID 10213683. 
  29. ^ In 2010, evidence was presented that seems to attribute the use of stone tools to Australopithecus afarensis, close to a million years before the first appearance of Homo. McPherron, S. P.; Alemseged, Z.; Marean, C. W.; Wynn, J. G.; Reed, D.; Geraads, D.; Bobe, R.; Bearat, H. A. (2010). "Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia". Nature. 466: 857–860. doi:10.1038/nature09248. PMID 20703305.  "The oldest direct evidence of stone tool manufacture comes from Gona (Ethiopia) and dates to between 2.6 and 2.5 million years (Myr) ago. [...] Here we report stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia [... showing] unambiguous stone-tool cut marks for flesh removal [..., dated] to between 3.42 and 3.24 Myr ago [...] Our discovery extends by approximately 800,000 years the antiquity of stone tools and of stone-tool-assisted consumption of ungulates by hominins; furthermore, this behaviour can now be attributed to Australopithecus afarensis."
  30. ^ Erin N. DiMaggio EN; Campisano CJ; Rowan J; Dupont-Nivet G; Deino AL; et al. (2015). "Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar, Ethiopia". Science. 347: 1355–1359. doi:10.1126/science.aaa1415. PMID 25739409.  See also: "Oldest known member of human family found in Ethiopia". New Scientist. 4 March 2015. Retrieved 7 March 2015. , Ghosh, Pallab (4 March 2015). "'First human' discovered in Ethiopia". BBC News. Retrieved 5 March 2015. 
  31. ^ Cela-Conde and Ayala (2003) recognize five genera within Hominina: Ardipithecus, Australopithecus (including Paranthropus), Homo (including Kenyanthropus), Praeanthropus (including Orrorin), and Sahelanthropus. Cela-Conde, C. J.; Ayala, F. J. (2003). "Genera of the human lineage". Proceedings of the National Academy of Sciences. 100 (13): 7684–7689. doi:10.1073/pnas.0832372100. PMC 164648Freely accessible. PMID 12794185. 
  32. ^ "A partial maxilla assigned to H. habilis reliably demonstrates that this species survived until later than previously recognized, making an anagenetic relationship with H. erectus unlikely. The discovery of a particularly small calvaria of H. erectus indicates that this taxon overlapped in size with H. habilis, and may have shown marked sexual dimorphism. The new fossils confirm the distinctiveness of H. habilis and H. erectus, independently of overall cranial size, and suggest that these two early taxa were living broadly sympatrically in the same lake basin for almost half a million years." Spoor, F; Leakey, M.G; Gathogo, P.N; Brown, F.H; Antón, S.C; McDougall, I; Kiarie, C; Manthi, F.K.; Leakey, L.N. (2007). "Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya". Nature. 448 (7154): 688–691. doi:10.1038/nature05986. PMID 17687323. 
  33. ^ Green, RE; Krause, J; et al. (2010). "A draft sequence of the Neanderthal genome". Science. 328 (5979): 710–22. doi:10.1126/science.1188021. PMID 20448178. 
  34. ^ Reich, D; Green, RE; Kircher, M; et al. (December 2010). "(December 2010). "Genetic history of an archaic hominin group from Denisova Cave in Siberia"". Nature. 468 (7327): 1053–60. doi:10.1038/nature09710. PMID 21179161. 
  35. ^ Reich; et al. (October 2011). "Denisova admixture and the first modern human dispersals into southeast Asia and Oceania". Am J Hum Genet. 89 (4): 516–28. doi:10.1016/j.ajhg.2011.09.005. PMC 3188841Freely accessible. PMID 21944045. 
  36. ^ Biological Anthropology: 2nd Edition. 2009. Craig Stanford et al.
  37. ^ Shaun Smillie, "Homo naledi—New human ancestor buried its dead," Times Live, 10 Sept 2015.
  38. ^ Berger, Lee R.; et al. (10 September 2015). "Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa". eLife. 4. doi:10.7554/eLife.09560. Retrieved 10 September 2015. Lay summary. 
    Full list of authors: Lee R Berger, John Hawks, Darryl J de Ruiter, Steven E Churchill, Peter Schmid, Lucas K Delezene, Tracy L Kivell, Heather M Garvin, Scott A Williams, Jeremy M DeSilva, Matthew M Skinner, Charles M Musiba, Noel Cameron, Trenton W Holliday, William Harcourt-Smith, Rebecca R Ackermann, Markus Bastir, Barry Bogin, Debra Bolter, Juliet Brophy, Zachary D Cofran, Kimberly A Congdon, Andrew S Deane, Mana Dembo, Michelle Drapeau, Marina C Elliott, Elen M Feuerriegel, Daniel Garcia-Martinez, David J Green, Alia Gurtov, Joel D Irish, Ashley Kruger, Myra F Laird, Damiano Marchi, Marc R Meyer, Shahed Nalla, Enquye W Negash, Caley M Orr, Davorka Radovcic, Lauren Schroeder, Jill E Scott, Zachary Throckmorton, Matthew W Tocheri, Caroline VanSickle, Christopher S Walker, Pianpian Wei, Bernhard Zipfel.
  39. ^ Schrenk, Friedemann; Kullmer, Ottmar; Bromage, Timothy (2007). "The Earliest Putative Homo Fossils". In Henke, Winfried; Tattersall, Ian. Handbook of Paleoanthropology. 1. In collaboration with Thorolf Hardt. Berlin, Heidelberg: Springer. pp. 1611–1631. doi:10.1007/978-3-540-33761-4_52. ISBN 978-3-540-32474-4.  Confirmed H. habilis fossils are dated to between 2.1 and 1.5 million years ago. This date range overlaps with the emergence of Homo erectus. Wilford, John Noble (August 9, 2007). "Fossils in Kenya Challenge Linear Evolution". The New York Times. Retrieved 2015-05-04. 
  40. ^ Haviland, William A.; Walrath, Dana; Prins, Harald E. L.; McBride, Bunny (2007). Evolution and Prehistory: The Human Challenge (8th ed.). Belmont, CA: Thomson Wadsworth. p. 162. ISBN 978-0-495-38190-7. H. erectus may have appeared some 2 million years ago. Fossils dated to as much as 1.8 million years ago have been found both in Africa and in Southeast Asia, and the oldest fossils by a narrow margin (1.85 to 1.77 million years ago) were found in the Caucasus, so that it is unclear whether H. erectus emerged in Africa and migrated to Eurasia, or if, conversely, it evolved in Eurasia and migrated back to Africa.
  41. ^ Now also included in H. erectus are Peking Man (formerly Sinanthropus pekinensis) and Java Man (formerly Pithecanthropus erectus). H. erectus is now grouped into various subspecies, including Homo erectus erectus, Homo erectus yuanmouensis, Homo erectus lantianensis, Homo erectus nankinensis, Homo erectus pekinensis, Homo erectus palaeojavanicus, Homo erectus soloensis, Homo erectus tautavelensis, Homo erectus georgicus. The distinction from descendant species such as Homo ergaster, Homo floresiensis, Homo antecessor, Homo heidelbergensis and indeed Homo sapiens is not entirely clear.
  42. ^ Curnoe, Darren (June 2010). "A review of early Homo in southern Africa focusing on cranial, mandibular and dental remains, with the description of a new species (Homo gautengensis sp. nov.)". HOMO - Journal of Comparative Human Biology. Amsterdam, the Netherlands: Elsevier. 61 (3): 151–177. doi:10.1016/j.jchb.2010.04.002. ISSN 0018-442X. PMID 20466364.  A species proposed in 2010 based on the fossil remains of three individuals dated between 1.9 and 0.6 million years ago. The same fossils were also classified as H. habilis, H. ergaster or Australopithecus by other anthropologists.
  43. ^ Hazarika, Manjil (2007). "Homo erectus/ergaster and Out of Africa: Recent Developments in Paleoanthropology and Prehistoric Archaeology" (PDF). EAA Summer School eBook. 1. European Anthropological Association. pp. 35–41. Retrieved 2015-05-04.  "Intensive Course in Biological Anthrpology, 1st Summer School of the European Anthropological Association, 16–30 June, 2007, Prague, Czech Republic"
  44. ^ The type fossil is Mauer 1, dated to ca. 0.6 million years ago. The transition from H. heidelbergensis to H. neanderthalensis at about 0.35 to 0.25 million years ago is largely conventional. Relevant examples are fossils found at Bilzingsleben (also classified as Homo erectus bilzingslebensis).
  45. ^ Bischoff, James L.; Shamp, Donald D.; Aramburu, Arantza; et al. (March 2003). "The Sima de los Huesos Hominids Date to Beyond U/Th Equilibrium (>350 kyr) and Perhaps to 400–500 kyr: New Radiometric Dates". Journal of Archaeological Science. Amsterdam, the Netherlands: Elsevier. 30 (3): 275–280. doi:10.1006/jasc.2002.0834. ISSN 0305-4403.  The first humans with "proto-Neanderthal traits" lived in Eurasia as early as 0.6 to 0.35 million years ago (classified as H. heidelbergensis, also called a chronospecies because it represents a chronological grouping rather than being based on clear morphological distinctions from either H. erectus or H. neanderthalensis), with the first "true Neanderthals" appearing between 0.25 and 0.2 million years ago.
  46. ^ Chang, Chun-Hsiang; Kaifu, Yousuke; Takai, Masanaru; Kono, Reiko T.; Grün, Rainer; Matsu’ura, Shuji; Kinsley, Les; Lin, Liang-Kong (2015). "The first archaic Homo from Taiwan". Nature Communications. 6: 6037. doi:10.1038/ncomms7037. 
  47. ^ "Fossil Reanalysis Pushes Back Origin of Homo sapiens". Scientific American. Stuttgart: Georg von Holtzbrinck Publishing Group. February 17, 2005. ISSN 0036-8733. Retrieved 2015-05-04.  The oldest fossil remains of anatomically modern humans are the Omo remains, which date to 195,000 (±5,000) years ago and include two partial skulls as well as arm, leg, foot and pelvis bones.

Further reading

External links

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