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List of human evolution fossils
The following tables give an overview of notable finds of hominin fossils and remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the human and chimpanzee lineages) in the late Miocene, roughly 7 to 8 million years ago.
As there are thousands of fossils, mostly fragmentary, often consisting of single bones or isolated teeth with complete skulls and skeletons rare, this overview is not complete, but show some of the most important findings. The fossils are arranged by approximate age as determined by radiometric dating and/or incremental dating and the species name represents current consensus if there is no clear scientific consensus the other possible classifications are indicated.
The early fossils shown are not considered ancestors to Homo sapiens but are closely related to ancestors and are therefore important to the study of the lineage. After 1.5 million years ago (extinction of Paranthropus), all fossils shown are human (genus Homo). After 11,500 years ago (11.5 ka, beginning of the Holocene), all fossils shown are Homo sapiens (anatomically modern humans), illustrating recent divergence in the formation of modern human sub-populations.
There are three scenarios that might account for the morphological details in the Qesem teeth. The first one is of a local archaic Homo population occupying southwest Asia during the Middle Pleistocene, to which the Qesem specimens would be attributed. Perhaps relevant in this regard, the Qesem lithic assemblages studied to date indicate a local origin, with no evidence of African and or European cultural affinities (Barkai et al., 2005 Gopher et al., 2005 Barkai et al., 2009). Albeit the lack of other diagnostic Middle Pleistocene SW Asian teeth, considering the evidence in its entirety, we believe that the Qesem ‘‘package’’ is more Skhul/Qafzeh like, even if some of its features are plesiomorphous.
Nowhere in this conclusion do the authors say that these teeth belong to Homo sapiens. Nowhere do they say they have just doubled the age of our species. Nowhere do they say that our species evolved in the Near East, not in Africa. There are only some vague hints that the teeth might be “Skhul/Qafzeh-like.” Or they might be something else.
While the paper itself is non-commital in its conclusions, it contains lots of good detail about the teeth, which is why it probably got accepted at the American Journal of Physical Anthropology. Who knows how some reporter got the idea that scientists had discovered the oldest fossils of Homo sapiens? It does seem that one of the authors has played footsie with reporters, offering some tasty quote-bait:
Nucleotide Site Patterns
Although our method can accommodate complex models, we work here with a four-population model of history (Fig. 1A), which has broad empirical support (11, 12). In this model, Neanderthals ( N ) contribute genes to Eurasians ( Y ) but not to Africans ( X ). The model allows no gene flow from Denisovans ( D ), for reasons explained below. Combinations of uppercase letters, such as N D , refer to the population ancestral to N and D . Lowercase letters, such as n and d , refer to individual haploid genomes sampled from these populations.
(A) Population tree representing an African population, X a Eurasian population, Y Neanderthals, N and Denisovans, D . The model involves admixture, m N time parameters, T i and population sizes, N i . (B) Population tree with embedded gene tree. A mutation on the solid red branch would generate site pattern y n (shown in red at the base of the tree). One on the solid blue branch would generate y n d . Mutations on the dashed black branches would be ignored. “0” and “1” represent the ancestral and derived alleles.
The gene tree describes how genes coalesce within the tree of populations. Fig. 1B illustrates one of many possible gene trees. Although closely linked nucleotide sites tend to share the same gene tree, this is not the case for sites farther apart on the chromosome, and any set of autosomal sequence data will encompass a multitude of gene trees.
The gene tree determines opportunities for allele sharing among samples. For example, a mutation on the solid red branch in Fig. 1B would be present in y and n but absent in x and d . We refer to this as the “ y n site pattern.” Similarly, a mutation on the solid blue branch would generate site pattern y n d . In a four-population model, there are 10 polymorphic site patterns, excluding singletons. We can tabulate their frequencies in sequence data and calculate their probabilities given particular population histories. Our program, legofit (described in Section S1), estimates parameters by fitting observed to expected frequencies. Whereas ABBA-BABA statistics use only 2 site patterns (“ABBA” and “BABA”), legofit uses all 10. This allows it to estimate additional parameters and avoid the biases discussed above.
A new look at old fossils
This latest piece of research did not involve the discovery of new fossils to fill in gaps in the record, but rather the analysis of existing data using a quantitative approach. This means taking detailed measurements of the shape of hominin teeth and calculating the rate or speed at which they changed over time.
'I am not estimating the date of divergence,' explains Aida. 'Rather, I am just calculating the rate of change in the teeth assuming different divergence times.'
This is an important, although slightly complicated, point. Aida logged the changes in the tooth shape of Neanderthals over time. Then she mapped this onto the evolutionary tree of hominins and modelled what would happen to this evolutionary rate of change if the split between modern humans and Neanderthals took place at different points in history.
'If you have a very young divergence time what we see is a very high evolutionary rate for the change in Neanderthal teeth shape, and if we have a very old divergence time then we have a very low evolutionary rate,' says Aida.
'In all the other branches on the hominin tree we can see that there are much lower evolutionary rates, so what I was looking for was the point where the rates that I see for both Neanderthals and other hominins match.'
The first skull of Homo neanderthalensis dates to around 50,000 years ago, but the species first evolved much earlier than this © The Trustees of the Natural History Museum, London
From this, Aida arrived at a date of divergence between 1.2 million and 800,000 years ago. 'This result is not based on general similarities and descriptions, but on a quantitative analysis,' she says.
'Of course, the analysis is based on some assumptions - and it can be argued that those inferences could be different - but this is a numerical analysis that anybody can repeat using the same or different assumptions.'
Homo Heidelbergensis & Early Neanderthal Fossil Sites - History
Here’s the short answer to the above question: Neanderthals lived in Europe and the Middle East during the Middle to Late Pleistocene, about 130,000 to about 30,000 years ago. But of course this topic is far more complicated even those dates are highly contested among researchers! Other questions include: how did Neanderthals get to be in Europe in the first place? Did their range change throughout time? What sorts of locations did they like to make their homes? And how do archaeologists know all this stuff anyway? Each of these questions, and more, will be discussed below.
Where did Neanderthals come from?
Unlike modern humans and most other hominids, Neanderthals did not arise out of Africa they are indigenous to Europe. Although the exact ancestry of Neanderthals is not known for certain, a general picture can be reconstructed as follows:
The first hominids to leave Africa, Homo erectus spread throughout the Middle East, Asia, and Europe. By 1.8 million years ago, groups of H.erectus had migrated as far as Dmanisi, Georgia 2 . (Some, like the creator of the diagram on the left, consider the African and European H. erectus to be a separate species, H. ergaster, but for present purposes the distinction doesn’t matter.) These hominids made tools of the Acheulean tradition. This would remain the same until the advent of the Neanderthal Mousterian industry.
Homo heidelbergensis evolved from H. erectus during Middle Pleistocene. There is presently debate about whether the species first appeared in southern Africa, east Africa or southern Europe. The youngest of these H. heidelbergensis remains have been dated to 300,000 years ago 1 . It is widely believed that an European population of H. heidelbergensis gave rise to Neanderthals, and due to the similarity and variability of bodily features, skeletons of H. heidelbergensis are sometimes studied as proto-Neanderthals. The more recent discoveries of Homo antecessor in Spain may be a link between H. erectus and H. heidelbergensis 8 .
The first evidence for “true” Neanderthals shows up by about 130,000 years ago.
Neanderthals core home range appears to be in southern and southwestern Europe, particularly southwestern France, Italy and the Gibraltar region of Spain 10 this is where Neanderthals lived the longest and where archaeologists find sites most abundantly. From there, the Neanderthals spread north into England, east as far as Denisova, Siberia 9 , and southeast into the Levant.
The spread and contraction of Neanderthal territory has been attributed to fluctuations in climate over time, with the Neanderthals retreating into their core area when weather became especially cold 11 . One can correlate the glacial OIS stages with hiatuses in habitation of sites in Germany, Bavaria, and Poland and other parts of central Europe Neanderthals did not occupy the sites during the Late Glacial Maximum 11 There are also similar lapses in habitation in Northwest Europe 10 . On the other hand, in Italian 11 and Iberian 5 sites that would have been included in this core area, there is no disruption in Neanderthal inhabitation, even during the Late Glacial Maximum.
There are over two hundred known Neanderthal archaeological sites throughout Europe and the Near East. Neanderthal fossil remains have not been found at all these locations, but those without them contain just as much useful materials for study, such as tools Neanderthals made and the bones of animals they ate. While Neanderthals probably spent far more time outside caves than inside them, many of the famous Neanderthal bones and artifacts have been discovered in caves. This is because caves’ cool, often dry environments are ideal for preservation of bones and other organic materials, and the sediments are less likely to be disturbed.
- Atapuerca is a large site in Spain with several different areas. The Sima de los Huesos is notable for containing the well-preserved skeletons of various ages. One hundred and sixty of these individuals have been assigned to the species Homo heidelbergensis. At Sima de los Elefantes, the remains of six H. antecessor individuals were found. 1
- Chapelle-aux-Saints, in central France, was occupied by Neanderthals who made tools of the Mousterian industry, and includes a contested burial. 6
- Grotte du Renne, at Arcy-sur-Cure in France, dates to the Upper and Middle Paleolithic, and contains remains of Neanderthals associated with tools of the Châtelperronian industry. 4 There were also items of personal ornamentation (such as beads) found at the site however, it is highly possible that these were more recent artifacts that were mixed in from a later level 7 .
- La Ferrassie, in southwestern France, consists of a cave and two rockshelters. Mousterian, Aurignacian, and Châtelperronian tools have all been found here this indicates both AMH and Neanderthal inhabitants, although at different points in time. Neanderthal remains at the site show possible burial 6 .
- La Quina is a site in southwest France dating to between 40-48,000 years ago. It is noted for its large Mousterian stone tool assemblage 6 .
Shanidar Cave, which dates to sixty to eighty thousand years ago, is a Neanderthal site in modern-day Iraq. The excavations of this site are important when considering the question of whether Neanderthals buried their dead 12 .
- Skhul Cave, in Israel, is a site that was inhabited by AMH during the Middle Pleistocene 6 . These AMH may have coexisted and possibly interacted with nearby Neanderthals. The Qafzeh rockshelter is very similar.
- Tabun Cave, also in Israel, contained the remains of a Neanderthal as well as Acheulean and Mousterian stone tools 6 . A similar site is Kebara Cave.
How do we know this stuff?
All archaeologists use the principles of stratigraphy (how sediments are organized in layers) to begin to analyze their data. In general, the further down an archaeologist digs, the older the artifacts and remains she finds will be. So, if Neanderthal tools are found in a sediment level below one in which there are AMH tools, this could be interpreted as Neanderthals having lived at the site before modern humans. However, stratigraphy alone can only tell us the age of remains relative to other remains, artifacts, or sediment layers we cannot get numerical dates. Additionally, sometimes an event like a landslide can mix up the layers, or erosion from wind or water can bring old materials to the surface. Or the people who find the artifacts/remains are not archaeologists at all, but miners, and therefore aren’t paying close attention to the stratigraphy!
Beginning in the 1950s, archaeologists have used lab methods such as radiocarbon dating, electron spin resonance, and thermoluminescence to date their finds. These methods have let archaeologists to date Neanderthal remains and artifacts with much greater precision than ever before, provide another line of evidence (or not) for established chronologies, and have allowed researchers to study remains that were found in poor or difficult to interpret stratigraphic contexts.
Since Carbon-14, which occurs in all once-living things, degrades over time, an archaeologist can estimate the age of a material based on how much 14 C is left in the sample. Radiocarbon dating is useful for dating organic materials (like bones, charcoal, or seeds) from a few hundred to 45 thousand years old. Therefore, 14 C dating is useful to date sites from the Upper Paleolithic and sites from the very end of the Neanderthals’ time range. The biggest problem with radiometric methods like 14 C dating is the danger of contamination from modern materials. Additionally, since the results are reported as a range due to potential of error (the range for 14 C dating can span a few thousand years), attempting fine grained research at sites like Kebara Cave can be difficult and controversial 12 .
Electron spin resonance (ESR) and thermoluminescence (TL) are both electron trap techniques. They work by exciting electrons in the material’s crystalline structure. For ESR testing, the researchers estimate the amount of electrons that are overexcited in the lattice structure. ESR can be used to date materials from a few thousand to about two million years old. In TL, the material is heated, and, based on the amount of light it gives off, can be dated (with an error range). ESR is particularly helpful because it can be used to date teeth and has been used at sites like Atapuerca 1 , and thermoluminescence dating is frequently employed on burnt stone tools.
To summarize, one last time: Neanderthals were an indigenous European hominid that lived in Europe and the Near East during the Middle and Late Pleistocene. Although they dispersed further, their core range was in Southern Europe, and they retreated back there when times were climatically harsh. Archaeologists can trace these patterns by analyzing data using a variety of techniques.
Although we know far more about Neanderthals than we did when they were first discovered (or even fifty years ago),just as many questions remain. As the body of research on the subject of Neanderthals grows, however, the picture will only get clearer.
1 J. L. Bischoff et al. (2003). "The Sima de los Huesos Hominids Date to Beyond U/Th Equilibrium (>350 kyr) and Perhaps to 400–500 kyr: New Radiometric Dates". J. Archaeol. Sci. 30 (30): 275
2 Boyd, Robert, and Joan B. Silk. How humans evolved. 6 ed. New York, NY : Norton, 2012. p. 279
3 Goldberg, P. & Bar-Yosef, O., "Site formation processes in Kebara and Hayonim Caves and their significance in Levantine Prehistoric caves", in T. Akazawa, K. Aoki and O. Bar-Yosef (eds), Neandertals and Modern Humans in Western Asia, New York & London: Plenum Press, 1998
4 Higham T, Jacobi R, Julien M, David F, Basell L, Wood R, Davies W, Ramsey CB.C (2010). Chronology of the Grotte du Renne (France) and implications for the context of ornaments and human remains within the Chatelperronian. PNAS
5 Jennings, Richard, Clive Finlayson, Darren Fa, and Geraldine Finlayson. "Southern Iberia As A Refuge For The Last Neanderthal Populations." Journal of Biogeography 38, no. 10 (2011): 1873-1885.
6 Klein, Richard G.. The human career: human biological and cultural origins. 3rd ed. Chicago: University of Chicago Press, 2009. Print.
7 Mellars P. (2010). Neanderthal symbolism and ornament manufacture: The bursting of a bubble? PNAS
8 Parfitt.S et al (2006) '700,000 years old: found in Pakefield', British Archaeology, January/February 2006
9 Reich, David Green, Richard E. Kircher, Martin Krause, Johannes Patterson, Nick Durand, Eric Y. Viola, Bence Briggs, Adrian W. et al. (2010), "Genetic history of an archaic hominin group from Denisova Cave in Siberia", Nature 468 (7327): 1053–1060
10 Roebroeks, Wil, Jean-Jacques Hublin, and Katharine MacDonald. "Continuities and discontinuities in Neandertal presence: A closer look at northwestern Europe." In The ancient human occupation of Britain. Amsterdam, The Netherlands: Elsevier, 2011. 113-123.
11 Serangeli, Jordi, and Michael Bolus. "Out of Europe-- the dispersal of a successful European hominin form." Quartar 55 (2008): 83-98.
12 Sommer, DJ, (1999) The Shanidar IV 'Flower Burial': a Re-evaluation of Neanderthal Burial Ritual, Cambridge Archaeological Journal, vol. 9(1), pp. 127-129
Theories of development
Josef Perner , Frank Esken , in Developmental Review , 2015
The thrust of this paper was to argue that the “cooperative turn”, which hypothetically may have emerged in Homo heidelbergensis around 400,000 years ago, has its main roots in the evolution of teleological reasoning in Homo. This new form of reasoning emerges in the transition from understanding behaviour as following causal regularities to understanding behaviour as actions for good reasons. In contrast to the mentalistic assumption that reasons are internal mental states, we argue that they are, on a fundamental level, objective and public facts in the world. While mentalistic explanations assume that understanding actions as intentional actions presupposes an understanding of internal mental states, the teleological approach argues that intentional actions are those for which there are observable good reasons that justify the behaviour. The teleological approach therefore rejects the claim that understanding others as acting for reasons requires understanding them as mental agents with individually different perspectives. We have shown that this theoretical framework can account for the difference in cooperativeness between young children and our evolutionary relatives and a development in stages – Piagetian in flavour – from a purely cybernetic understanding of behaviour to understanding objective reasons, to finally subjective reasons for acting.
Homo Heidelbergensis & Early Neanderthal Fossil Sites - History
This puts the species Homo heidelbergensis back at the heart of human evolution as the last common ancestor that we, Homo sapiens, shared with Neanderthals, Homo neanderthalensis, says Stringer, the Museum's Research Leader in Human Origins.
The Status of Homo heidelbergensis study, which was published in the journal Evolutionary Anthropology this week, reviews the fossil and DNA evidence for the existence of heidelbergensis and its place in the human family tree.
Central to the discussion is the important site of La Sima de los Huesos (meaning 'Pit of the bones'), in Atapuerca, northern Spain. It has yielded more than 6,000 fossils from about 28 individuals.
They had been identified as H. heidelbergensis by the team who originally discovered the fossils, and have been estimated to be about 600,000 years old. For some palaeontologists, such as Stringer, this has confused ideas about where heidelbergensis sits in the human family tree.
Now, however, Stringer says there is enough fossil and genetic evidence to say that the Sima material belongs to early Neanderthals, and also that it must be much younger than 600,000 years old.
"Most of the data supporting this view actually come from studies by the Atapuerca team themselves," says Stringer. "They have shown that the skulls, jaws, teeth and skeletons of the Sima fossils show many Neanderthal features."
Fossil skull of Homo heidelbergensis.The Neanderthal features include a little pit in the middle of the occipital bone at the back of the skull, the shape of the face, and the patterns of cusps on the teeth.
Ancestor of modern humans too
Because they classified the Sima material as heidelbergensis, the Atapuerca team regarded heidelbergensis, with all its Neanderthal features, as the ancestor to Neanderthals only.
However, other palaeontologists, including Stringer, consider heidelbergensis to also be the ancestor of modern humans. They believed that heidelbergensis was a widespread species, which in Africa gave rise to H. sapiens, and in Europe and Asia gave rise to the Neanderthals. But the classification and date of the Sima fossils published by the Atapuerca team contradicted this idea.
2 reconstructions of recent human evolution, one with an early date for the Sima fossils and their classification as Homo heidelbergensis (left), the other with them positioned as early Neanderthals and a later date (right). In this 2nd reconstruction the Denisovans are added as a possible early branch from the Neanderthal lineage.Fossil dates
No other fossils with Neanderthal features have been dated to earlier than about 400,000 years ago. Stringer explains, "We would not expect clear Neanderthal traits to occur 200,000 years earlier than this."
"Dating these bones to such a great age greatly complicates our picture of human evolution half a million years ago."
Both morphological and genetic studies have suggested that Neanderthals and modern humans began to branch away from each other about 400,000 years ago.
So the Sima material cannot be 600,000 years old, and must be at least 200,000 years younger, says Stringer.
The Sima fossils are too old to be radiocarbon dated, so scientists have tried various other techniques to estimate their age. One method was to use the decay of radioactive isotopes to date the stalagmite that overlies the human fossils.
Reclassifying the Sima fossils as Neanderthals rather than heidelbergensis puts heidelbergensis back at the heart of human evolution as the last common ancestor.The first analysis suggested an age of around 350,000 years, but later measurements suggested an age closer to 600,000 years. "I think they got it right the first time," says Stringer.
Back as a common ancestor
Reclassifying the Sima fossils from heidelbergensis to early Neanderthal gives a clearer picture of the position of heidelbergensis in the human family tree, and also clarifies the pattern of human evolution in Europe.
"Removing the Sima fossils from heidelbergensis means that the species once again makes a good common ancestor for the Neanderthals, modern humans, and probably the Denisovans (known from DNA recovered from fragmentary fossils in Siberia) too," says Stringer.
"These new views on the dating and classification of the Sima material have led to a constructive scientific debate with the Atapuerca team, which will help to progress our understanding of the place of these important fossils in human evolution," Stringer concludes.
The Status of Homo heidelbergensis is published in the journal Evolutionary Anthropology.
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'Virtual fossil' reveals last common ancestor of humans and NeanderthalsTop: Modern human skull from 19th century South Africa. Now part of the Duckworth Collection at the Leverhulme Centre for Human Evolutionary Studies, University of Cambridge.Middle: 'Virtual fossil' of Last Common AncestorBottom: Neanderthal skull found in La Ferrassie, France, and dating from 53 to 66 thousand years ago. Now curated in the Musée de l'Homme in Paris. Credit: Dr. Aurélien Mounier
We know we share a common ancestor with Neanderthals, the extinct species that were our closest prehistoric relatives. But what this ancient ancestral population looked like remains a mystery, as fossils from the Middle Pleistocene period, during which the lineage split, are extremely scarce and fragmentary.
Now, researchers have applied digital 'morphometrics' and statistical algorithms to cranial fossils from across the evolutionary story of both species, and recreated in 3D the skull of the last common ancestor of Homo sapiens and Neanderthals for the first time.
The 'virtual fossil' has been simulated by plotting a total of 797 'landmarks' on the cranium of fossilised skulls stretching over almost two million years of Homo history—including a 1.6 million-year-old Homo erectus fossil, Neanderthal crania found in Europe and even 19th century skulls from the Duckworth collection in Cambridge.
The landmarks on these samples provided an evolutionary framework from which researchers could predict a timeline for the skull structure, or 'morphology', of our ancient ancestors. They then fed a digitally-scanned modern skull into the timeline, warping the skull to fit the landmarks as they shifted through history.
This allowed researchers to work out how the morphology of both species may have converged in the last common ancestor's skull during the Middle Pleistocene—an era dating from approximately 800 to 100 thousand years ago.
The team generated three possible ancestral skull shapes that corresponded to three different predicted split times between the two lineages. They digitally rendered complete skulls and then compared them to the few original fossils and bone fragments of the Pleistocene age.
This enabled the researchers to narrow down which virtual skull was the best fit for the ancestor we share with Neanderthals, and which timeframe was most likely for that last common ancestor to have existed.
Previous estimates based on ancient DNA have predicted the last common ancestor lived around 400,000 years ago. However, results from the 'virtual fossil' show the ancestral skull morphology closest to fossil fragments from the Middle Pleistocene suggests a lineage split of around 700,000 years ago, and that—while this ancestral population was also present across Eurasia—the last common ancestor most likely originated in Africa.
The results of the study are published in the Journal of Human Evolution.
"We know we share a common ancestor with Neanderthals, but what did it look like? And how do we know the rare fragments of fossil we find are truly from this past ancestral population? Many controversies in human evolution arise from these uncertainties," said the study's lead author Dr Aurélien Mounier, a researcher at Cambridge University's Leverhulme Centre for Human Evolutionary Studies (LCHES).
"We wanted to try an innovative solution to deal with the imperfections of the fossil record: a combination of 3D digital methods and statistical estimation techniques. This allowed us to predict mathematically and then recreate virtually skull fossils of the last common ancestor of modern humans and Neanderthals, using a simple and consensual 'tree of life' for the genus Homo," he said.
The virtual 3D ancestral skull bears early hallmarks of both species. For example, it shows the initial budding of what in Neanderthals would become the 'occipital bun': the prominent bulge at the back of the skull that contributed to elongated shape of a Neanderthal head.The 'virtual fossil' of last common ancestor of humans and Neanderthals as hypothesized in the new study. Credit: Dr. Aurélien Mounier
However, the face of the virtual ancestor shows hints of the strong indention that modern humans have under the cheekbones, contributing to our more delicate facial features. In Neanderthals, this area—the maxillia—is 'pneumatized', meaning it was thicker bone due to more air pockets, so that the face of a Neanderthal would have protruded.
Research from New York University published last week showed that bone deposits continued to build on the faces of Neanderthal children during the first years of their life.
The heavy, thickset brow of the virtual ancestor is characteristic of the hominin lineage, very similar to early Homo as well as Neanderthal, but lost in modern humans. Mounier says the virtual fossil is more reminiscent of Neanderthals overall, but that this is unsurprising as taking the timeline as a whole it is Homo sapiens who deviate from the ancestral trajectory in terms of skull structure.
"The possibility of a higher rate of morphological change in the modern human lineage suggested by our results would be consistent with periods of major demographic change and genetic drift, which is part of the history of a species that went from being a small population in Africa to more than seven billion people today," said co-author Dr Marta Mirazón Lahr, also from Cambridge's LCHES.
The population of last common ancestors was probably part of the species Homo heidelbergensis in its broadest sense, says Mounier. This was a species of Homo that lived in Africa, Europe and western Asia between 700 and 300 thousand years ago.
For their next project, Mounier and colleagues have started working on a model of the last common ancestor of Homo and chimpanzees. "Our models are not the exact truth, but in the absence of fossils these new methods can be used to test hypotheses for any palaeontological question, whether it is horses or dinosaurs," he said.