The Human Family Tree, It Turns Out, Is Complicated

We are not the man that we were. In the past 20 years genomics, paleoanthropology, and ancient DNA have combined forces to completely rewrite our knowledge of the origins of our species. Even the most simplistic of imaginings, the complexity and diversity of human evolution over the past few hundred years is more impressive than those we had just a few generations ago. However, we now have a more complex and messy story. It turns out that our species status is complex.The orthodoxy in 2000 was that humans originated from Africa 60,000 years ago. Neanderthals, and other human groups, were considered evolutionary dead ends. This tidy tale of us is no longer able to pass basic facts checks.Razib KhanThe 2010 genomes of ancient Eurasian archaic hominins1 were found to match modern human genetics2. We also had to accept the fact that only 2 to 3 percent are Neanderthals in human ancestry outside of Africa. About 5 percent of Melanesian groups like the Papuans from New Guinea's ancestry comes from a new human lineage that was discovered in Denisova Cave in Siberia.The genetic picture has become more complicated since these major overhauls. The genetic picture has become more complex since these first major overhauls.Even the Out of Africa migration7 has been less tidy than we expected. You can be an Amazonian native, an Australian indigenous person, or a German burgher outside Africa. However, 90 to 99 percent of your ancestry is derived from one ancestral human population pulse that occurred 60,000 years ago. They reached Australia by 50,000 years of age after a small, isolated tribe of African people of 1,000 to 10,000 people became genetically homogenous because they had a small initial population. They had succeeded the Denisovans and Neanderthals around 40,000 years ago. They even moved to North and South America around 15,000 years ago.The story inside Africa is richer, and still not fully understood.10 Many African people began to separate from one another 200,000 years ago and became distinct lineages like the Khoisan or West Africans. Modern humans emerged within Africa not as an explosion but rather through the gradual evolution of interconnected lineages. It was a slow process.11 Who knows? Who knows? At this stage, we don't know. It's best to admit that this chapter is only a preliminary one.WikipediaIt's raining menNew dramatis persons, mostly ghosts, are constantly appearing on stage left. This complicates what was once a simple soliloquy. Carl Zimmer of The New York Times reports on a well-preserved fossil. The discovery of Dragon Man Skulls in China May Add Species To Human Family Tree12. An Israeli team has published a paper in Science about a population that was discovered in Israel. It dates back to between 120,000 and 140,000 years ago. The skull of Dragon Man, which is approximately 140,000 years old is very well preserved and shows a mix of modern and primitive features.WikipediaThese fossils are new and there is no consensus on their authenticity. Some researchers would like to name Dragon Man Homo Longi (pronounced "lng", being Chinese for dragon) a new species of human. They claim that its features are more closely related to modern humans to Neanderthals.The majority of Paleoanthropologists working outside China believe Dragon Man to be the paradigm-busting species that we only know definitively through genomics. The faction points out that Dragon Man was a large-sized human with massive teeth. This is similar to a confirmed Denisovan jaw found in Tibet in 2019.13 Why do other paleoanthropologists disagree? They performed an evolutionary analysis using all the characteristics of the skull. Unfortunately, the results did not yield DNA. Homo longi is closer to modern humans on this inferred family tree. Genomics, however, shows that Denisovans are closer to Neanderthals and modern humans.My guess is that Homo longi, Denisovans, are one and the exact same. Or, to be more precise, Homolongi is one of many Denisovan linesages. The phylogenetic analysis of this species revealed that it has both modern and archaic characteristics. However, physical characteristics are not as informative about lineages relationships as DNA. This is due to several factors. There are several reasons for this. First, there are tens to millions of human genomes that can be used as reference points for relationships.14 Physical traits can only be measured in hundreds of phenotypic characteristics (how many ways could you determine the shape of your skull or the size of your teeth?). Second, DNA is free from subjective bias, which is a major advantage over assessed physical characteristics. The genomic position is A, B, C, G, or T. What physical characteristics will you be defining? How will you slice and dice the skull shape? Modern imaging has made it possible to use objective measurements, but humans still have the ability to decide what they should be measuring.WikipediaLastly, and most importantly, natural selection can affect physical characteristics.15 Two similar populations can have very different genetic makeups because adaptation drives convergence from different starting points to similar optimized external characteristics. In this instance, I believe the Neanderthals were able to adapt very well to North Eurasia's cold climate and evolved from many of our ancestral human characteristics.16 Yes, modern humans may be more primitive than their long-lost relatives. Modern humans and the Denisovans are likely to resemble one another, but the Neanderthals were highly-specialized in their adaptations. This is an example of evolution in overdrive.What about the Israeli find? The Nesha Ramla homo's discoverers also wanted to label it a new species, although one that is very similar to Neanderthals. It is not clear to me whether this is a new species. It is fascinating to me that they seem very different from modern humans and have advanced tool technology. According to the remains found at their sites, Nesha RAMla Homo hunted large and small game and used wood fires. These people clearly had cultural interactions with Africans and Neanderthals from the north.Our own lineage was presented in the Out of Africa narrative of 2000 as a superhuman race and the culmination of human evolution. As human brains got larger and more complex, the telos of 2,000,000 years of encephalization. These latest findings do not fit into the old hero story. The contest for the largest human brains is won by Neanderthals. Dragon Man also had a large brain, which is in line with modern cranial capabilities. Over the past few million years, all human lineages got bigger brains. This was not only the lineage that brought us up.WikipediaMany Denisovans lived among themWe must also acknowledge that our deep and intimate interest in Neanderthals could have led to us being misled when it came time to Denisovans. Neanderthals were found in Europe, which has the longest and best-funded archaeological tradition. It turns out that they are not typical archaic people. Genetic work has shown that Denisovans are not one lineage as was the case with Neanderthals. Instead, they were a variety of individuals that differ in their relationship to the Denisova Cave genome sequences. It is evident that the Denisovan ancestry of Papuans differs from the Siberian Denisovan sequencings. Geographically, the most distant Denisovan groups, Siberia and Wallacea, are likely to be far more genetically distinct from one another than Khoisan is from the rest. Based on your assumptions, the most distant Denisovan lines probably split into distinct populations 200,000 to 400,000 year before they died.Instead of thinking about three major human species from 60,000 years ago we might think of two families, one homogeneous and one related (modern humans and Denisovan people) The Denisovans were more closely related than modern humans to Neanderthals. Their common ancestors emigrated from Africa 600,000 to 750,000 centuries ago. They then split into two branches: the western (Neanderthal), and the eastern (Denisovan). The evolutionary history of Denisovans might share more similarities with their African ancestors than it does with their Neanderthal counterparts. They lived in a more restricted and dangerously forbidding environment in the northern ecozone of Africa. The Pleistocene was harsh and cold across the globe, but East Asia provided more refuges for Denisovans than West Eurasia for Neanderthals18, which was isolated from African escapes through the Mediterranean and harsh deserts. This is why Neanderthals were close to extinction many times, but Denisovans remained diverse and varied through the last 100,000 years.WikipediaThere are many more options!The main characters in the story of our species' recent origins are the Neanderthals and Denisovans. Today, there is only one human species on the planet. However, this is an extraordinary moment. There have been many human species for most of the last few million years. We have strong evidence that small, specialized species of humans existed in Southeast Asia, such as the pygmy Hobbits or Homo luzonensis, up until about 50,000 years ago. They are not only different from one another, but also from modern humans, Denisovans and Neanderthals. There were probably many different African populations that were absorbed over time, much like the Denisovans or Neanderthals. Homo naledi, South Africa's ancestor, survived almost all the way to the time of modern humans arriving on the continent 200,000 years ago.A lot of circumstantial archaeological evidence and genetic evidence suggests that earlier African lineages linked to modern humans expanded into eastern Eurasia prior to our own expansion. Sumatra20 and China19 artifacts from before 60,000 years ago are suspiciously modern. Genetic analysis of Siberian Neanderthals from 120,000 years ago indicates that there was admixture with populations related to modern humans. It is possible that Homolongi may descend from one of these earlier populations. This can only be proven by DNA, as most fossil remains older than 100 years old don't yield any genetic material. However, this skull is sufficiently old to have produced DNA in perfect conditions.Also in Evolution the Mate Selection Trapdoor by Michael J. Ryan. The evolution of sexual beauty in all species is a continuous experiment. There are many variations in courtship traits that can be observed and these are quickly dismissed by the choosers. However, new efforts at...READ MOREWe pruned the branchesThey were genetically a fairly homogeneous mammalian specie, and experienced rapid expansion after a small ancestral population. This is especially true for people outside of Africa. All non-Africans have a common ancestry. This traces back to a tiny human population of 1,000 to 10,000 that exploded across Eurasia in one sweep. Although Africa has a more complex structure than the rest of the world, many of its deep differences can be attributed to the large number of remnant hunter-gatherer communities21: Hadza, Khoisan Bushmen and Pygmies in the rainforest. Despite the fact that there were fewer founding groups for African farmers, their expansion has been rapid. However, they have experienced less restriction than non-Africans.It was very different from today's planet 100,000 years ago. If we could go back in time and look at the diversity of human life on its surface, it would surprise us by how diverse it is. We know very little about the history of modern humans and Neanderthals. There were also at least three to four types of Denisovans and two pygmy Homo population in Southeast Asia. There were likely to be a remnant Homo Erectus in Southeast Asia, as well as other divergent lineages within Africa and a new Homo Nesher Ramla in Israel in the Middle East that shares affinities with Neanderthals.Paleoanthropology's first 20 years have been some of the most exciting since its inception. This is largely due to the rapid rise of paleogenetics. There is no reason to believe that the wave has peaked. As the 2020s approach, I can't wait to update my knowledge on humanity.Razib Khan works as a population geneticist. Follow Razib Khan on Twitter @razibkhanThis article was originally published by Razib Khans Substack and Unsupervised Learning. It is reprinted with permission.Image of the lead image: IR Stone / ShutterstockRefer to1. Reich, D., and al. Genetic history of an archaic hominin family from Denisova Cave, Siberia. Nature 468, 1053-1060 (2010).2. Thompson, L. Complete Neanderthal genome sequenced. NIH News (2010).3. Jacobs, G.S. et al. Multiple Denisovan ancestries are deeply divergent in Papuans. Cell 177, 1010-1021(2019).4. M. Africans have a surprising amount of Neanderthal DNA, according to Price. Science (2020).5. Durvasula A. Sankararaman (S.) Recovering signs of ghost archaic intrusion in African populations. Science Advances 6, Eaax5097 (2020).6. Gibbons, A. Multiple attempts with human ancestors were made by mysterious ghost populations. Science (2020).7. Cann, R.L. Stoneking, M., and WIlson A.C. Mitochondrial genome and human evolution. Nature 325, 31–36 (1987).8. Henn B.M. Cavalli-Sfrza L.L. & Feldman M.W. The great human expansion. Proceedings of the National Academy of the Sciences, 109, 17758-17764 (2012).9. Reich, D., and others. Reconstructing the history of Native American populations. Nature 488, 374-374 (2012).10. Schlebusch C.M. Schlebusch, C.M. Annual Review of Genomics and Human Genetics 19, 405-428 (2018).11. Scerri, E.M. & Chikhim L. & Thomas M.G. Beyond simple out-of Africa and multiregional models of human evolution. Nature Ecology & Evolution 3, 1370-1372 (2018).12. Zimmer, C. The discovery of a dragon man skull in China could add species to the human family tree. The New York Times (2021).13. Chen, F., and others. An early middle Pleistocene Denisovan denisovan mandible taken from the Tibetan Plateau. Nature 569, 409-412 (1999).14. The 1000 Genomes Project Consortium. Global reference for human genetic variation. Nature 526, pages 68-74 (2015).15. L. Deng and S. Xu. Adaptation to human skin color in different populations. Hereditas 155 (2018).16. Wroe S., Computer simulations have shown that Neanderthal facial morphology is adaptation to high energy and cold, but not heavy biting. Proceedings of the Royal Society B285 (2018).17. Browning S.R. Browning B.L. Browning Zhou Y., Tucci S., & Akey J.M. Analysing sequence data from humans reveals two pulses containing archaic Denisovian mixture. Cell 173, 53-61 (2018).18. Song, W., and others. Multiple refugia found in East Asia's penultimate glaciations are shown by ecological modeling of an insect pest and phylogeography. BMC Evolutionary Biology 18, 150 (2018).19. Curnoe D., Ji X. Tacon, P.S.C. & Yaozheng G. Possible signs of hominin-hybridization in the early Holocene of Southwest China Science Reports 5, 12408 (2015).20. Westaway, K.E. et al. Sumatra was home to an early modern human population 73,000-63,000 years ago. Nature 548, 322-325 (2016).21. Callaway, E. Ancient African genomes provide a glimpse into early human history. Nature (2020).