Human Origins

It has been reported in PlosONE that analysis of bones found in Yunnan Province, China have revealed a possibly new species of Hominid, closely related to us but having "primitive characteristics", who lived some 11,000 to 14,000 years ago. They have been dubbed "The Red Deer Cave People". 

While this may indeed be a separate taxon, or a further "archaic" form of Homo sapiens, morphology alone cannot be used any more as the sole basis on which to be the end all of taxonomy.  If DNA can be extracted from these guys, their relationship to present day peoples can be more definitively examined.

Photos and illustrations by Darren Curnoe and Peter Shouten.

http://www.dailymail.co.uk/sciencetech/article-2114867/Fossil-suggests-new-hominid-species-Stone-Age-cavemen-Red-deer-people-discovered-China.html 

The Max Planck Institute has revealed that it has completely decoded the genome of the Denisovans, a hitherto unknown sister species to both ourselves and Neandertals.

The whole genome is available at the following websites:
http://www.eva.mpg.de/denisova
 http://aws.amazon.com/datasets/2357

A recent study from the University of Uppsala reveals that not only do we have further evidence of admixture between Neandertals and Denisovans with anatomically modern Homo sapiens in Asia, but also that there was admixture between the Denisovans and Neandertals themselves.  Additionally,  it appears that the unique DNA markers from Denisovans does not appear in North American populations, indicating that the Asian Denisovan admixture occured less than 30,000 years BP!

It's pretty amazing to me that the science of genetics is rewriting, and writing, what we know of human origins.  Particularly, virtually nothing was known about Denisovans until very recently, and then, only from a finger bone.  

The abstract and citations follow.
Archaic human ancestry in East Asia

1. Pontus Skoglunda,1 and 
2. Mattias Jakobssona,b,1

+Author Affiliations

1. aDepartment of Evolutionary Biology and
2. bScience for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden

1. Edited by Richard G. Klein, Stanford University, Stanford, CA, and approved September 27, 2011 (received for review May 23, 2011)
   
   

AbstractRecent studies of ancient genomes have suggested that gene flow from archaic hominin groups to the ancestors of modern humans occurred on two separate occasions during the modern human expansion out of Africa. At the same time, decreasing levels of human genetic diversity have been found at increasing distance from Africa as a consequence of human expansion out of Africa. We analyzed the signal of archaic ancestry in modern human populations, and we investigated how serial founder models of human expansion affect the signal of archaic ancestry using simulations. For descendants of an archaic admixture event, we show that genetic drift coupled with ascertainment bias for common alleles can cause artificial but largely predictable differences in similarity to archaic genomes. In genotype data from non-Africans, this effect results in a biased genetic similarity to Neandertals with increasing distance from Africa. However, in addition to the previously reported gene flow between Neandertals and non-Africans as well as gene flow between an archaic human population from Siberia (“Denisovans”) and Oceanians, we found a significant affinity between East Asians, particularly Southeast Asians, and the Denisova genome—a pattern that is not expected under a model of solely Neandertal admixture in the ancestry of East Asians. These results suggest admixture between Denisovans or a Denisova-related population and the ancestors of East Asians, and that the history of anatomically modern and archaic humans might be more complex than previously proposed.
http://www.pnas.org/content/108/45/18301 
Shared genes with Neanderthal relatives not unusual28 October 2011 Uppsala Universitet

• Under embargo until 31 October 2011 20:00 GMT

During human evolution our ancestors mated with Neanderthals, but also with other related hominids. In this week’s online edition of PNAS, researchers from Uppsala University are publishing findings showing that people in East Asia share genetic material with Denisovans, who got the name from the cave in Siberia where they were first found.

-      Our study covers a larger part of the world than earlier studies, and it is clear that it is not as simple as we previously thought. Hybridization took place at several points in evolution, and the genetic traces of this can be found in several places in the world. We’ll probably be uncovering more events like these, says Mattias Jakobsson, who conducted the study together with Pontus Skoglund.

Previous studies have found two separate hybridization events between so-called archaic humans (different from modern humans in both genetics and morphology) and the ancestors of modern humans after their emergence from Africa: hybridization between Neanderthals and the ancestors of modern humans outside of Africa and hybridization between Denisovans and the ancestors of indigenous Oceanians. The genetic difference between Neandertals and Denisovans is roughly as great as the maximal level of variation among us modern humans.

The Uppsala scientists’ study demonstrates that hybridization also occurred on the East Asian mainland. The connection was discovered by using genotype data in order to obtain a larger data set. Complete genomes of modern humans are only available from some dozen individuals today, whereas genotype data is available from thousands of individuals. These genetic data can be compared with genome sequences from Neandertals and a Denisovan which have been determined from archeological material. Only a pinky finger and a tooth have been described from the latter.

Genotype data stems from genetic research where hundreds of thousands of genetic variants from test panels are gathered on a chip. However, this process leads to unusual variants not being included, which can lead to biases if the material is treated as if it consisted of complete genomes. Skoglund and Jakobsson used advanced computer simulations to determine what this source of error means for comparisons with archaic genes and have thereby been able to use genetic data from more than 1,500 modern humans from all over the world.

-         We found that individuals from mainly Southeast Asia have a higher proportion of Denisova-related genetic variants than people from other parts of the world, such as Europe, America, West and Central Asia, and Africa. The findings show that gene flow from archaic human groups also occurred on the Asian mainland, says Mattias Jakobsson.

-         While we can see that genetic material of archaic humans lives on to a greater extent than what was previously thought, we still know very little about the history of these groups and when their contacts with modern humans occurred, says Pontus Skoglund.

Because they find Denisova-related gene variants in Southeast Asia and Oceania, but not in Europe and America, the researchers suggest that hybridization with Denisova man took place about 20,000–40,000 years ago, but could also have occurred earlier. This is long after the branch that became modern humans split off from the branch that led to Neandertals and Denisovans some 300,000-500,000 years ago.

- With more complete genomes from modern humans and more analyses of fossil material, it will be possible to describe our prehistory with considerably greater accuracy and richer detail, says Mattias Jakobsson.

• Full bibliographic informationArchaic human ancestry in East Asia
  Pontus Skoglunda,1 and Mattias Jakobssona,b,1
  aDepartment of Evolutionary Biology and bScience for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
  Edited by Richard G. Klein, Stanford University, Stanford, CA, and approved September 27, 2011 (received for review May 23, 2011)
  ARTICLE #201108181
  www.pnas.org/cgi/doi/10.1073/pnas.1108181108

A new study has revealed that modern Asians have 1% unique Denisovan DNA, revealing that modern humans pretty much mated with anything that moved.  It also reveals that humans have always moved around, and these simplistic ideas of "one migration out of Africa", or "a replacement migration out of Africa" are all humbug.  Humans have moved in and out of Africa constantly, and into and out of Europe, and into Asia and all around.

A new study by Michael Hammer takes a look at the human genome and concludes that our direct ancestors in Africa had some degree of admixture with the archaic forms of our genus, such as Homo erectus.  The approach appears to be different than the Max Planck Institute's extraction of Neandertal DNA and comparing with modern populations.  Looking at six modern African populations, it has been deduced that there were 'anomalies' in the modern genome.  So, up to 2% of uniquely archaic genes have been discovered to have been contributed to modern Africans genome about 35,000 years ago by a population that 'diverged about 700,000 years ago' from our line.

This admixture could have been from  Homo erectus or the other taxa that we have identified as H. rudolphensis or H. ergaster, etc.  

I think that the old ideas of species, and variation and typology in terms of morphology have to give way to the genetics and the genetic sequencing technology of today.  

The abstract appears below:
Genetic evidence for archaic admixture in Africa

1. Michael F. Hammera,b,1, 
2. August E. Woernera, 
3. Fernando L. Mendezb,
4. Joseph C. Watkinsc, and 
5. Jeffrey D. Walld

+Author Affiliations

1. aArizona Research Laboratories Division of Biotechnology,
2. bDepartment of Ecology and Evolutionary Biology, and
3. cMathematics Department, University of Arizona, Tucson, AZ 85721; and
4. dInstitute for Human Genetics, University of California, San Francisco, CA 94143

1. Edited by Ofer Bar-Yosef, Harvard University, Cambridge, MA, and approved July 27, 2011 (received for review June 13, 2011)
   
   

AbstractA long-debated question concerns the fate of archaic forms of the genus Homo: did they go extinct without interbreeding with anatomically modern humans, or are their genes present in contemporary populations? This question is typically focused on the genetic contribution of archaic forms outside of Africa. Here we use DNA sequence data gathered from 61 noncoding autosomal regions in a sample of three sub-Saharan African populations (Mandenka, Biaka, and San) to test models of African archaic admixture. We use two complementary approximate-likelihood approaches and a model of human evolution that involves recent population structure, with and without gene flow from an archaic population. Extensive simulation results reject the null model of no admixture and allow us to infer that contemporary African populations contain a small proportion of genetic material (≈2%) that introgressed ≈35 kya from an archaic population that split from the ancestors of anatomically modern humans ≈700 kya. Three candidate regions showing deep haplotype divergence, unusual patterns of linkage disequilibrium, and small basal clade size are identified and the distributions of introgressive haplotypes surveyed in a sample of populations from across sub-Saharan Africa. One candidate locus with an unusual segment of DNA that extends for >31 kb on chromosome 4 seems to have introgressed into modern Africans from a now-extinct taxon that may have lived in central Africa. Taken together our results suggest that polymorphisms present in extant populations introgressed via relatively recent interbreeding with hominin forms that diverged from the ancestors of modern humans in the Lower-Middle Pleistocene.

A new study finds that, due to a virtual 'swarm' of anatomically modern humans swamped the Neandertals, physically crowding them out, outcompeting them for scarce resources, and marginalizing them to the point of their extinction.

The study appears Science: http://www.sciencemag.org/content/333/6042/623

Science Daily has a nice summary of the article here:http://www.sciencedaily.com/releases/2011/07/110728144928.htm
Firstly, here is my take on this study:


Neandertals did go extinct but have also been found to have contributed to anatomically modern humans through admixture in the Levant.  The findings of the study copied below are sound, but not terribly profound.  Resource partitioning of competing species or populations or subspecies is usually determined by the carrying capacity of the environment.  Hominids have been able to "cheat" a little here, with the cultural innovation of sophisticated tool making to give them a survival 'hand', as it were.  However, some of the findings are tenuous at best, by suggesting that Neandertal social constructs or communication were less well developed than the newcomers.  The reason cited is the sudden appearance of sophisticated art, cited as proof of the anatomically modern humans ability to communicate and their more sophisticated social organization, all of which are conclusions based on assumptions and surmised without necessarily taking into account that symbolic expression through art does not mean well developed social communication or organizational skills:  most artists work alone and do not collaborate, nor communicate particularly well.  Additionally, the archaeological classifications of 'who made what, when and how' in terms of Mousterian lithics (found in context with both Neandertal and anatomically modern human remains), and lithics found not in association with any remains further making assumptions that this 'further lithic type' was a Neandertal or early modern human unique type, may blur some of the statistical findings.  Still, Neandertals did become extinct and this study provides a quantitative analysis as the basis for a mechanism on which this new theory resides.  But it has some problems, nonetheless.  --James Zaworski

The Science Daily summary is copied and pasted here:ScienceDaily (July 29, 2011) — 

New research sheds light on why, after 300,000 years of domination, European Neanderthals abruptly disappeared. Researchers from the University of Cambridge have discovered that modern humans coming from Africa swarmed the region, arriving with over ten times the population as the Neanderthal inhabitants.

The reasons for the relatively sudden disappearance of the European Neanderthal populations across the continent around 40,000 years ago has for long remained one of the great mysteries of human evolution. After 300 millennia of living, and evidently flourishing, in the cold, sub-glacial environments of central and western Europe, they were rapidly replaced over all areas of the continent by new, anatomically and genetically 'modern' (i.e. Homo sapiens) populations who had originated and evolved in the vastly different tropical environments of Africa.

The most plausible answer to this long-debated question has now been published in the journal Science by two researchers from the Department of Archaeology at Cambridge -- Professor Sir Paul Mellars, Professor Emeritus of Prehistory and Human Evolution, and Jennifer French, a second-year PhD student.

By conducting a detailed statistical analysis of the archaeological evidence from the classic 'Perigord' region of southwestern France, which contains the largest concentration of Neanderthal and early modern human sites in Europe, they have found clear evidence that the earliest modern human populations penetrated the region in at least ten times larger numbers than those of the local Neanderthal populations already established in the same regions. This is reflected in a sharp increase in the total number of occupied sites, much higher densities of occupation residues (i.e. stone tools and animal food remains) in the sites, and bigger areas of occupation in the sites, revealing the formation of much larger and apparently more socially integrated social groupings.

Faced with this dramatic increase in the incoming modern human population, the capacity of the local Neanderthal groups to compete for the same range of living sites, the same range of animal food supplies (principally reindeer, horse, bison and red deer), and the same scarce fuel supplies to tide the groups over the extremely harsh glacial winters, would have been massively undermined. Additionally, almost inevitably, repeated conflicts or confrontations between the two populations would arise for occupation of the most attractive locations and richest food supplies, in which the increased numbers and more highly coordinated activities of the modern human groups would ensure their success over the Neanderthal groups.

The archaeological evidence also strongly suggests that the incoming modern groups possessed superior hunting technologies and equipment (e.g. more effective and long-range hunting spears), and probably more efficient procedures for processing and storing food supplies over the prolonged and exceptionally cold glacial winters. They also appear to have had more wide-ranging social contacts with adjacent human groups to allow for trade and exchange of essential food supplies in times of food scarcity.

Whether the incoming modern human groups also possessed more highly developed brains and associated mental capacities than the Neanderthals remains at present a matter of intense debate. But the sudden appearance of a wide range of complex and sophisticated art forms (including cave paintings), the large-scale production of elaborate decorative items (such as perforated stone and ivory beads, and imported sea shells), and clearly 'symbolic' systems of markings on bone and ivory tools -- all entirely lacking among the preceding Neanderthals -- strongly point to more elaborate systems of social communications among the modern groups, probably accompanied by more advanced and complex forms of language.

All of these new and more complex behavioural patterns can be shown to have developed first among the ancestral AfricanHomo sapiens populations, at least 20,0000 to 30,000 years before their dispersal from Africa, and progressive colonisation (and replacement of earlier populations) across all regions of Europe and Asia from around 60,000 years onwards.

If, as the latest genetic evidence strongly suggests, the AfricanHomo sapiens and European Neanderthal populations had been evolving separately for at least half a million years, then the emergence of some significant contrasts in the mental capacities of the two lineages would not be a particularly surprising development, in evolutionary terms.

Professor Sir Paul Mellars, Professor Emeritus of Prehistory and Human Evolution at the Department of Archaeology, said: "In any event, it was clearly this range of new technological and behavioural innovations which allowed the modern human populations to invade and survive in much larger population numbers than those of the preceding Neanderthals across the whole of the European continent. Faced with this kind of competition, the Neanderthals seem to have retreated initially into more marginal and less attractive regions of the continent and eventually -- within a space of at most a few thousand years -- for their populations to have declined to extinction -- perhaps accelerated further by sudden climatic deterioration across the continent around 40,000 years ago."

Whatever the precise cultural, behavioural and intellectual contrasts between the Neanderthals and intrusive modern human populations, this new study published in Sciencedemonstrates for the first time the massive numerical supremacy of the earliest modern human populations in western Europe, compared with those of the preceding Neanderthals, and thereby largely resolves one of the most controversial and long-running debates over the rapid decline and extinction of the enigmatic Neanderthal populations

Non-Africans are part Neandertal, a new study confirms.2010 saw a remarkable genetic study concerning human evolution and our relationship with Neandertals: we interbred at least at one point, or several points, in our parallel histories.

The history of Neandertals (also spelled Neanderthal), has been controversial ever since their bones were discovered in a valley in Germany in the 19th century. Their relationship to us has been equally controversial, as at times they were considered our very primitive direct ancestor, a cousin species, a sister-species, a subspecies, or a distant cousin whom we outcompeted and replaced. 

That we are up to 4% unique Neandertal DNA was an amazing revelation last year by the Max Planck Institute study headed by Svante Paabo. A new study published in Molecular Biology and Evolution (http://mbe.oxfordjournals.org/content/28/7/1957) confirms this finding, and finds that even further, non-African populations have up to 9% unique Neandertal X-chromosome in our genetic make up. 

In 2004, I wrote an anthropological thesis for a seminar course predicting this admixture in the Levant, based on shared morphology, shared technology and culture, space and time.  It is refreshing to know that I was right all along, and that these genetic studies confirm my hypothesis.  And, I remain Z-andertal for your reading pleasure.

The abstract for this study follows:


An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations

AbstractRecent work on the Neandertal genome has raised the possibility of admixture between Neandertals and the expanding population of Homo sapiens who left Africa between 80 and 50 Kya (thousand years ago) to colonize the rest of the world. Here, we provide evidence of a notable presence (9% overall) of a Neandertal-derived X chromosome segment among all contemporary human populations outside Africa. Our analysis of 6,092 X-chromosomes from all inhabited continents supports earlier contentions that a mosaic of lineages of different time depths and different geographic provenance could have contributed to the genetic constitution of modern humans. It indicates a very early admixture between expanding African migrants and Neandertals prior to or very early on the route of the out-of-Africa expansion that led to the successful colonization of the planet.

A new genetic study based on the human genome project and comparisons of "regional genomes" has revealed that there was admixture after 60,000 years ago.  
For the first time genomic archaeologists are able to infer population size and history using single genomes, a technique that makes fewer assumptions than existing methods, allowing for more detailed insights. It provides a fresh view of the history of humankind from 10,000 to one million years ago.
From the abstract on Nature:Inference of human population history from individual whole-genome sequences
Nature (2011) doi:10.1038/nature10231Received 01 April 2009 Accepted 20 May 2011 Published online 13 July 2011The history of human population size is important for understanding human evolution. Various studies1, 2, 3, 4, 5 have found evidence for a founder event (bottleneck) in East Asian and European populations, associated with the human dispersal out-of-Africa event around 60 thousand years (kyr) ago. However, these studies have had to assume simplified demographic models with few parameters, and they do not provide a precise date for the start and stop times of the bottleneck. Here, with fewer assumptions on population size changes, we present a more detailed history of human population sizes between approximately ten thousand and a million years ago, using the pairwise sequentially Markovian coalescent model applied to the complete diploid genome sequences of a Chinese male (YH)6, a Korean male (SJK)7, three European individuals (J. C. Venter8, NA12891 and NA12878 (ref. 9)) and two Yoruba males (NA18507 (ref. 10) and NA19239). We infer that European and Chinese populations had very similar population-size histories before 10–20kyr ago. Both populations experienced a severe bottleneck 10–60kyr ago, whereas African populations experienced a milder bottleneck from which they recovered earlier. All three populations have an elevated effective population size between 60 and 250kyr ago, possibly due to population substructure11. We also infer that the differentiation of genetically modern humans may have started as early as 100–120kyr ago12, but considerable genetic exchanges may still have occurred until 20–40kyr ago.My take: While this is an important study, it is involving inferences, and these inferences are based on assumptions that the mutation rates are predictible and constant in DNA.  This has not been quantitatively demonstrated, in my opinion, and this study needs to be augmented by the fossil record and through archaeological study.

The mammoth carved in bone discovered in Florida is 13,000 years old, according to a report in National Geographic News.  This is a significant find, and is, to date, the oldest "art" discovered from North America.  

Becoming Human: NOVA’s Three Part Series Evolves Nicely. 

By 

James Zaworski 

NOVA is a great science series aired on PBS, The Public Broadcasting System. I have been a regular viewer, reluctantly and voluntarily, for the past thirty years. NOVA broaches the field of paleoanthropology, one that is dear to my heart. In short, we get a rather up to date look at human origins. Well, at least that is what the producers thought. Just prior to the airing of the program in 2009, a major discovery, that of Ardipithecus ramidus, as one of our earliest ancestors, was announced. Oops! Still, the program has its merits, and what follows is a synopsis and review of the three part series. 

Becoming Human: Part 1. First Steps. 

Who are we? Where did we come from? When did we begin? Such questions have plagued our species since we became self aware. The fossil record is extremely sparse, and our ‘family tree’ is being written, and re-written, as discoveries are made. 

We all know about Charles Darwin and his theory of evolution by natural selection, so eloquently expressed in his “Origin of Species”, published in 1859. Darwin rightly postulated that humans evolved in Africa, and that a “missing link” remained to be discovered. Several“missing links” have been found in Africa, among them in the 1950s “Zinj”(Zinjanthropus), and “Handy Man”(Homo habilis), both discovered in Olduvai Gorge, Kenya by Louis Leakey, as well as “Lucy” (Australopithecus afarensis) discovered by Don Johansen in Ethiopia in 1974, to “Turkana Boy”(Homo erectus), discovered by Richard Leakey in Kenya in the 1980s. Each in its own time had been hailed as “the missing link”, and as our direct ancestor. Many discoveries have been made since, and the ‘family tree’ has proved to be quite ‘bushy’, as it were. 

Our closest living relatives are the apes, particularly the chimpanzee and gorilla. When did our common ancestor live? According the estimates from both the ‘molecular clock’ and the fossil record, the dates of our common ancestor is dated between 5 and 7 million years ago. However, the fossil record has been pretty scarce beyond 4 million years ago. At least, this has been true until recently. 

Two major traits, walking on two legs, or bipedalism, a very terrestrial adaptation, and an increasing brain size, or encephalization, are the anatomical hallmarks of our species. Contrasted to our ape relatives, chimps and gorillas move around on all fours, exhibiting quadrapedalism, and being arboreal in habit. Chimps and gorillas also have comparatively small brains as compared with ours. 

What paleoanthropologists expected to find after Darwin was a large brained ape, which was embodied in the historic hoax of Piltdown Man. However, what was found in the fossil record, going back at least 4-5 million years, is a small brained bipedal ape, an ape with a chimp sized brain but one who was adapted to walking on two legs. 

First steps looks at three fossils in particular, Sahelanthopus, and two Australopithecus afarensis. The Sahelanthopus is a very ancient, and controversial, ape fossil that may or may not be in our family tree. It has not been ascertained with certainty if it is indeed a bipedal creature. The other two that have been found are “Lucy” and a baby, nicknamed “Salaam”, or “peace”. 
What drove our evolution? Paleoclimatologists and geologists have been able to piece together the ancient climate and environment, and what made us “come down from the trees” appears to have been climate change. The rain forests began to disappear, as the climate dried, creating savannahs and grasslands. However, for at least two million years, there was a wild fluctuation in climate, and it is during this time that stone tools began to appear, as well as an increase in brain size. The great leap forward for us was Homo habilis, or “Handy Man”, the maker of the first stone tools. Another driver of our evolution appears to be bipedalism: this is a more efficient way of getting around. Going about on all fours is a very energy consuming locomotion system. 

Becoming Human: Part 2 Birth of Humanity. 

Episode two begins with the development of our genus, Homo. We start with Homo erectus, the descendant of Homo habilis, and our probably ancestor. We begin with Richard and Maeve Leakey’s discovery of “Turkana Boy”, a nearly complete Homo erectus youth. This was the most complete Homo erectus ever found, over 1.5 million years old. He is not just so very complete, he is not fully grown at 5 foot, three inches tall. How old was he? At first, he was thought to be 13 to 15 years old, but upon further examination, through CT scanning technology, we can see his dentition and unerupted teeth, putting him at a spry 8 years old! 5ַ” at 8 years old! He is fully bipedal, with a postcranial skeleton nearly identical to ours. He is reconstructed, or “fleshed out”, by an anthropological artist, and he is surprisingly human looking. 

Why did he grow up so quickly? Perhaps this is tied to brain size. Chimps have a 400 cubic centimeter (cc) brain size. Ours is an average of 1200 cc’s. Turkana boy, at age 8, has a 900 cc brain, much closer to our brain size. Perhaps it means that even though Homo erectus is perhaps our direct ancestor, it also means that Turkana Boy was following a pattern of ape development, that is, rapid maturation. Humans have the longest ‘childhood’ of all Hominids. It is thought that a long development has a great deal to do with our cognitive development, and hence, long term survival. 

Episode 2 is all about Homo erectus, and its close relatives. These include Homo ergaster, found in modern day Georgia in southwest Asia. These fossils date to 1.8 million years ago, making this the earliest “out of Africa” Hominids known to date. H. ergaster was kind of intermediate between H. habilis and H. erectus, but may just be an early form of H. erectus. It all comes down to taxonomy, whether you are a lumper or a splitter. 

The discovery of Homo floriensis, or the “Hobbit”, a dwarf Hominid species which lived as recently as 18000 years BP, sheds light on the first “out of Africa” migration. When compared to H. ergaster, the morphological features of the skeleton are very complementary, albeit in dwarf size. Why did this species become a dwarf? Insular dwarfism, and gigantism, is a phenomenon that has been seen time and again in zoology and paleontology. Indeed, on Flores and Komodo lives the largest lizard in the world, the Komodo Dragon. There were dwarf elephants on Flores as well, called Stegadon. 

Episode 2 sets the stage for our ultimate evolution, in the concluding episode. 

Becoming Human: Part 3. The Last Human Standing. 

As recently as 50,000 years ago, there were up to four different species of humans living simultaneously, but today there is only one, us. Those four included Homo erectus, Homo floriensis, Homo neanderthalensis, and our species, Homo sapiens. Why did we survive, and the others become extinct? 

Episode three examines in detail the relationship between Neanderthal Man, and ourselves. Neanderthals are probably the most misunderstood, and misrepresented, human relative. As close as can come to our species, he has had a bad rap since his discovery in the 19th century. The fact of the matter is that the type specimen of Neanderthal was an aged, arthritic cripple. He has forever been given the dim witted ‘cave man’ image, despite the evidence found in further discoveries. For example, Neanderthals were the first people known to bury their dead, and not just bury their dead, but to bury them with ritual objects. They had sophisticated stone tool technology, called Mousterian, and this technology was also adopted by Cro-Magnon peoples when they made it to Europe. The Neanderthals had larger brains than our species. Their vocal apparatus was fully capable of producing complex language. They practiced both art and music. Neanderthals were also the first to live to older age, and they cared for the infirm, those not able to care for themselves. You never find old Homo erectus in the fossil record! In short, Neanderthals were the closest thing to us going. They were either a subspecies of ours, or a full species unto themselves, depending on the paleoanthropologist’s point of view. 

So, what happened to these ‘other humans’? They were either outcompeted for food and resources, killed off, interbred with, and replaced. Homo erectus lingered on to about 50,000 years ago in Indonesia, but were finally relaced by our species. Homo floriensis managed to hang on until 18,000 years ago, and became extinct. Neanderthals lasted until some 20,000 years ago before finally disappearing. 
Did we modern Europeans evolve directly from Neanderthals? It does not appear that there was enough time to do so, even with punctuated equilibrium. Analysis of Neanderthal DNA from 30,000 years ago shows enough difference in the nucleotides to suggest that we did not evolve from Neanderthals, but the evidence is not without its critics. 
One questions remains: did we interbreed with Neanderthals and did Europeans evolve directly from Neanderthals? There are some fossils that show features of both early modern humans and Neanderthals, but a consensus has not been reached. The molecular evidence says that Neanderthals diverged from us some 250,000 years ago. Neanderthals had a really great run: they lasted for more than 225,000 years. Our species has been around for less than half that time. 
What is clear is that our species, Homo sapiens, found itself the only Hominid remaining, and spread throughout the world, with our stone tool technology becoming increasingly sophisticated. Cave paintings , stylized Venus figurines, and complex culture and diverse languages contributed greatly to our supremacy. And it goes, from Neolithic to farming, settled village life to cities, the advent of writing, division of labor, social stratification, and civilizations, leading up to the present day. 

What I Like About “Becoming Human”. 

1. The Evidence. 

The evidence that is presented in this documentary series consists of the fossils themselves, stone tools and stone tool technology, geological evidence, and biological evidence in the form of DNA and molecular analysis. Some of the evidence is controversial, however. 

2. The Scientists 

In this three part series, you will see interviews and commentary from some of the great paleoanthropologists who have made the discoveries, such as Don Johansen, discoverer of Lucy, and Richard and Maeve Leakey, discoverers of many East African Hominids. There are stone tool experts, geneticists, biologists, paleozoologists, and geologists. 

3. New Perspectives 

Paleoanthropology is certainly one of the most interdisciplinary of the sciences, drawing upon archaeology, behavioral primatology, paleozoology, paleobotany, geology, chemistry, physics, climatology, genetics, biology, physiology, anatomy, osteology, pathology, and the behavioral sciences. Some new explanations are presented in the documentary series as well as alternate theories. 

What I Do Not Like About “Becoming Human”. 

1. Controversial Evidence 

Some of the evidence presented is quite controversial. For example, the so-called “Molecular Clock”. This “clock” postulates that the rate of mutation in DNA is constant, and not variable. The human-ape divergence is estimated at 5-7 million years ago, and has a ‘give or take’ margin of error of 2 million years! That’s a pretty significant margin of error! Furthermore, since nuclear DNA begins to break down at death, most DNA that we can salvage from fossils (the limit is about 30,000-40,000 year old fossils), is mitochondrial DNA. The Molecular Clock makes assumptions about mutations without direct evidence, and states that mutations occur at a constant and predictable rate, and doesn’t take into account punctuated equilibrium. 

2. Series Length 

This series is only 3 hours long. It is really too short, considering the vast amount of material that is presented and covered. The subject matter here could easily fill at 10-hour documentary series. The series is too short, and really only skims the surface, as far as I am concerned. 

3. Scientific Bias 

NOVA is usually a scientific series that seeks to present the facts, as well as some controversy, and give two sides, and leave it up for the viewer to make up his mind based on the arguments and evidence presented. Becoming Human doesn’t quite live up to this approach. 

However, all in all, I liked “Becoming Human”. While some of the conclusions may be biased, and some of the evidence controversial, and while being too short in length, “Becoming Human” presents the story of our origins from a scientific point of view, draws upon some well respected experts in the field, presents some new evidence, and gives us an entertaining and educational look at how we came to be who we are today. It is worth watching, and worth having in your library. 

Online resources 

http://www.pbs.org/wgbh/nova/beta/evolution/becoming-human-part-1.html 
http://www.pbs.org/wgbh/nova/beta/evolution/becoming-human-part-2.html 
http://www.pbs.org/wgbh/nova/beta/evolution/becoming-human-part-3.html 


http://www.epinions.com/review/NOVA_Becoming_Human/content_498333290116