Session 16: Episode 5(1) Introducing Episode 5, our ancient ancestors and their relatives William P. Hall President Kororoit Institute Proponents and Supporters Assoc., Inc. - http://kororoit.org william-hall@bigpond.com http://www.orgs-evolution-knowledge.net Access my research papers from Google Citations
Tonight Begins the last, largest and most complex episode in my fugue Explores & reconstructs the emergence and evolution of technologically assisted humanity and human organizations From: tool-using apes living 4-5 million years ago To: today s humano-technical individuals forming socio technical organizations Focus will be biological rather than a technological Part 1 of the episode sets out Basic concepts of evolutionary and comparative biology used in the reconstruction Summarizes the material (i.e., fossil, genomic & archaeological) evidence Extending Social Cognition and Emergence of Socio-Technical Organizations Introduction Material evidence: what we think we know about hominin evolution What fossils tell us about our pedigree and relationships Homo emerges and crosses the continents What comparative genomics tells us about our genealogy } Denisovans to be covered Neanderthals in contexts of What ancient tool-kits tell us about our ancestors later sessions
Introducing Episode 5 Goal: to explore and understand how our chimpanzee-like ancestors living in East African forests came to so completely dominate the biosphere of our entire planet that they threaten to destroy it Overwhelmed since 2010 with new and sometimes revolutionary information Impact of Moore s Law New technologies for anthropology, archaeology, cognitive science, genomics Ever-increasing scope and pace of research & publication Exploding volume of paleo and population genomic information Recent siblings in our family tree (Neanderthals, Denisovans, & other ghosts) Revealing the epic migrations of our ancestors Revolutionary science may be stabilizing into normal science Impacts of technological revolutions on our biology Positive feedback between technological and cognitive evolution Individual selection vs group selection in the evolution of human social systems
Four major sections 4 Material evidence what we think we know Reconstruction of the last 5 million years of human history An evolutionary hypothesis how did we get to where we are now? Working to understand what circumstances shaped our evolution to result in the observed history Role natural selection and coevolutionary feedback among Climate change Tool use Cognition Ecology Cooperation is innate Emergence of human social organizations as higher order living systems Moores Law and the rise and rise of socio-technical organizations Evolutionary processes working on higher orders of living things
MATERIAL EVIDENCE about HUMAN EVOLUTION What we think we know and How we know it
Lines of evidence 6 Comparative biology (close similarities infer common descent) Anatomy & physiology (determines capabilities) Behavior (shows us what can be done with the capabilities) Ecology (shows us what has been done) Palaeoarcheology (persistent artifacts) Where & when Tool kits tell us something about the tool-maker Genomics (complete genomes! 3 BN data points/individual!!) Fossil genomes back as far as 400 K years! Highly accurate pedigrees Confident inferences about population sizes & histories Fossils (surviving indicators of past existence) Where When (to some degree depending on dating evidence) How (depending on degree of completeness & associations) Inferred relationships Biogeography (reconstructions of migrations & adaptations)
Our ancestors were socially foraging, tool-using forest apes in East African Rift Valley 5 mya Adaptive plateaus achieved in the Pliocene as our ancestors became more bipedal and better adapted to open and arid environments (White et al. 2009) (click pictures below to view videos) 7 Chimps using probes to collect ants. Probe is inserted almost to full length into earth. Child watching mother crack otherwise inedible palm nuts using stone hammer & anvil.
Ancient tool kits Worked stones survive better than bones! Records existence of toolmaker and technology Time Place Complexity & sophistication show exponential increase over 3 my Wood & plant tools rarely fossilize 8
Comparative genomics 9 Divergence times of human's closest relatives based on complete genome sequencing (Locke et al. 2011).
Relationships based on anatomy & fossils 10 Early Miocene primates ~ 20 Mya several fruit eating, arboreal, ape-like primate species lived in tropical forests around the margins of the ancestral Mediterranean Tool use may be early development (see Orangutan pirates) gibbons & orangutans surviving lineages in SE Asian forests Homininae ancestors of all apes in Africa Humid forests offer poor conditions for fossil formation Late Miocene ~ 10 Mya in remaining African moist forests Gorilla lineage Hominini tool-using ancestors of chimpanzees and humans probably located in the southern & central areas of Africa Hominin & chimpanzee-bonobo lineages probably split 4-8 Mya Human ancestors probably cut off from chimpanzee stock by mountain building along W side of the Great Rift Valley and subject to increasing aridification Hominin history in the Rift zone documented by fossils
11 Approximate date ranges for fossil hominin species, which are defined according to both speciose and short taxonomies (after de Sousa & Cunha 2012) Splitters taxonomy Lumpers taxonomy Approximate date range Possible hominins Sahelanthropus tchlldensis Ardipithecus ramidus s.l. 7Ma Orrorin tugenensis Ardipithecus ramidus s.l. 6Ma Ardipithecus kadabba Ardipithecus ramidus s.l. 5.8-5.2Ma Ardipithecus ramidus Ardipithecus ramidus s.l. 4.5-4.3Ma Archaic hominins Australopithecus anamensis Australopithecus afarensis s.l. 4.2-3.9Ma Australopithecus afarensis Australopithecus afarensis s.l. 3.7-3Ma Australopithecus bahrelghazali Australopithecus afarensis s.l. 3.5-3.0Ma Kenyanthropus platyops Kenyanthropus platyops 3.5-3.3Ma Australopithecus africanus Australopithecus africanus 3-2.4Ma Australopithecus sediba Australopithecus sediba 1.95Ma Megadont archaic hominins Australopithecus garhi Australopithecus garhi 2.5Ma Paranthropus aethiopicus Paranthropus boisei s.l. 2.5-2.3Ma Paranthropus boisei s.s. Paranthropus boisei s.l. 2.3-1.4Ma Paranthropus robustus Paranthropus robustus 2.0-1.5Ma Transitional hominins Homo habilis s.s. Homo habilis s.l. 2A-1AMa Homo rudolfensis Homo habilis s.l. 2.4-1.6Ma Premodern Homo Homo erectus s.s. Homo erectus s.l. 1.9-1.5Ma Homo ergaster Homo erectus s.l. 1.8Ma-30ka Homo antecessor Homo antecessor 780-500ka Homo heidelbergensis Homo heidelbergensis 600-100ka Homo neanderthalensis Homo neanderthalensis 200-28ka Homo floresiensis Homo floresiensis 74-17ka Anatomically modern Homo Homo sapiens s.s. Homo sapiens s.l. 195ka-present Note 1: s.s., sensu stricto; s.l., sensu lata. Note 2. Genomic data argues that H. neanderthalensis, Denisovan Man, and H. heidelbergensis are not H. sapiens.
Some of the main hominin species recognized by fossils (~2010) 12 Homo floresiensis (the Hobbit ) is a dwarf hominin with some features more closely resembling Australopithecus than H. erectus, suggesting to some that Australopithecus may have colonized Asia before Homo did!
Critically informative species of Homo 13 H. naledi?? Wood, B. 2012. Facing up to complexity. Nature 488, 162-163 - http://tinyurl.com/k53ofwy. Dmanisi Georgia (Lordkipanidze et al. e.g., 2013) - Variation in H. georgicus shows H. erectus, ergaster, & probably also rudolfensis and habilis form one chronospecies persisting through time erectus longest lived Homo, spread widely through Africa and (via Dmanisi) Eurasia naledi newly discovered, small brained, mosaic of primitive and modern features floresiensis (Hobbit) lived up to a few thousand years ago on Flores (Indonesia) probably derived from erectus (Kubo et al. 2013). Modern sibling species: analysis of highly accurate genomes from modern sapiens and Denisovans (Meyer et al. 2012) & Neanderthals (Prüfer et al 2014) from Denisova Cave, Altai Mountains, Siberia show Evolutionary divergence ~ 300 kya, Limited interbreeding with introgression Hybrid infertility sufficient for effective isolation
Introducing some of the species
Fossils (1.8 my) first hominins out of Africa (?) ancestor/early Homo erectus Lordkipanidze, D., et al. 2013. A complete skull from Dmanisi, Georgia, and the evolutionary biology of early Homo. Science 342, 326-331 http://tinyurl.com/kbnwxnn. (Oct. 2013) 1.8 mya ~550-730 cc cranial capacity, fully bipedal, scavanged or hunted large game with Oldowan grade butchering tools; first hominins out of Africa (Hertler et al. 2013) Individual had been toothless for years before death, implying strong social support network? 15 Lordkipanidze, D., et al. 2005. The earliest toothless hominin skull. Nature 434, 717-718.
Homo naledi from Rising Star Cave system, 40 km N of Johannesburg, South Africa 16 Fossils found by cavers 2 years ago National Geographic funded 2 seasons Chamber where the remains were found could only be accessed by very small, skinny people More than 1500 pieces of at least 15 individuals, many lying on the soil surface, were recovered - many remain Dating difficult because not embedded in datable rocks and no other fossils found to allow comparative dating Documentation Berger, et al. 10/9/2015: formal description Dirks, et al. 10/9/2015: taphonomy Circumstances of the site strongly suggest deliberate burial Shreeve (2015): National Geographic story Stringer (2015): Reviews evidence & makes comparisons
17 Homo naledi, Berger, et al. 10/9/2015
Stringer (2015) 18 Cranial volume comparisons South Africa A. sediba South Africa A. africanus East Africa A. afarensis East Africa 1470 group East Africa 1813 group South Africa H. naledi East East Africa Africa unattributed All non-erectus non-erectus Homo Homo East Africa/ Georgia early H. erectus Range 420 385 571 400 550 750 * 510 660 * 565-560 630 680 510 750 546 1067 (with Dmanisi) 690 1067 (East Africa) Mean 459 478 586 650 629 787 (with Dmanisi) 863 (East Africa)
Shreeve (2015) National Geographic Where does naledi fit? Three hypotheses Homo floresiensis Dmanisi 19 Denisovan
The entire fossil record for Denisovans But the genome is wondrous! Fossilized part of smallest bone in little finger yielded 30+ complete genomes of a genetically distinct species from Neanderthal and sapiens 30+ complete copies (each with about 3 x 10 9 nucleotides for comparison with ancient Neanderthal and recent sapiens DNA 20 Prüfer, K., et al., Pääbo, S. 2014. The complete genome sequence of a Neanderthal from the Altai Mountains. Nature 505, 43 49 http://tinyurl.com/lvg96n2.
Homo floresiensis (the Hobbit ) 21 Brown et al. 2009 < 38 to 18 kya Cranial capacity 380-420 cc Tool users Colonists had to cross water Some critics argued that the specimens represented a pathological condition of microcephaly Additional individuals found, with current idea that they were normal individuals Some have even argued that floresiensis is closer to Australopithecus than Homo Luang Bua Cave, Flores Id., Indonesia
Out of Africa 22 Alternative hypotheses for early exits from Africa (after Rightmire & Lordkipanidze 2010). Top: one species (H. erectus) evolved in Africa and spread through Eurasia. Floresensis was an early offshoot of erectus Bottom: an early African Homo spread to Eurasia, giving rise to erectus in Asia, that then returned to Africa. floresiensis ancestors may have exited Africa prior to erectus Common ancestor to sapiens, neanderthalensis, & denisovans may be erectus or another independent exit from Africa
23 Temporal and geographic distribution of homo in the strict sense
Mechanics of human evolution
Genes & memes genetic vs cultural adaptation 25 Genes Determine individual anatomical, physiological and neurological capacities Mutation: physical change to one or more DNA nucleotides on a chromosome Change is slow multi-generational process depending on natural selection Movement rather than increased versatility Meme = unit of culture (an idea or value or pattern of behavior or knowledge) that may be passed between individuals or from one generation to another by non-genetic means Change often intra-generational depending on innovation, social relationships and processes Transmission limited by genetic capacity to communicate detailed information Essential information easily lost or corrupted over generations. Rate and extent of cultural accumulation depend on genetic capacity, group size, (culturally transmitted) cultural practices Major evolutionary trend in hominids is the growing importance of memetic evolution
Adaptation = application of genetic or cultural knowledge to solve problems of life Natural selection on genes works at the level of individual genetic variation depending on successes of carriers of particular genes in the population Selection on cultural knowledge works at the level of culturally variant groups, depending on successes of the different groups. A group whose shared cultural knowledge allows it to solve problems other groups can t solve grows at the expense of those other groups Successful items of cultural knowledge may be carried by individuals between groups to speed the evolutionary arms race Rate of cultural evolution depends on individuals genetically determined capacities to understand, remember, and transmit cultural knowledge 26
Niche shifts (left) vs niche expansions (right). Vertical axis represents survival probability of particular phenotypes. 27 Niche shift Mutation is blind Natural selection tracks current requirements, generally with continuing specialization Niche expansion Retain original adaptation together with adding new capabilities, i.e., accumulation or (very rare) cases of gene duplication and functional divergence New mutation crosses adaptive threshold opening new adaptive landscape (i.e., grade shift)
Next session covers primate genomics, our family tree and dispersal to the ends of the Earth Now that our ancestors and close relatives have been introduced we will consider the historical facts so far as they can be determined. From comparing fossils and genomic information we can construct a more-or-less detailed family tree going back a million years or so From fossils and toolkits we can reconstruct geographic distributions From data on geology, paleoclimates, fossils, and toolkits we can begin to reconstruct ancient ecologies and our ancestors relationships to their environments Fossils, tools, genomics and human migrations 28 Oldowan origins in the crucible of the Rift valley Out of Africa 1 (and 2?) what hominins from Dmanisi and Flores tell us Origin and spread of the Acheulean toolkit through Africa and Asia Fossil hominins in Europe prior to Homo sapiens Proliferation and genomics of the heidelbergensis species complex Triumph of anatomically modern Homo sapiens out of Africa to the world