Invaders Part 1 (PDF)

WSJ The Short Answer video re The Invaders https://www.wsj.com/video/dogs-may-have-played-role-i n-extinction-of-neanderthals/6DEC6FC3-B481-448D-A86 6-DD7DC1CCAA47.html  Today’s takeaways Who were the Neanderthals? Shipman’s hypothesis Modern humans’ spread into Eur...

WSJ The Short Answer video re The Invaders https://www.wsj.com/video/dogs-may-have-played-role-i n-extinction-of-neanderthals/6DEC6FC3-B481-448D-A86 6-DD7DC1CCAA47.html  Today’s takeaways Who were the Neanderthals? Shipman’s hypothesis Modern humans’ spread into Europe/Asia played a role in Neanderthal extinction New frame for human past Humans a form of invasive species ca. 40,000 years ago Human arrival Wolf-dogs with humans Neanderthal extinction aDNA studies Humans / Neanderthals exchanged genes (1-4%) Invasive species Species that moves into a new geogr. region Examples: Zebra mussel / Lionfish / Kudzu Invasive species Step 1: Landing – Typically transported by humans Inadvertently – bilge water Intentionally – Seafaring voyage to Australia 40,000 years ago Invasive species Step 2: Survival Need enough of species to persist Min. viable population Australia: arrival 45,000 years ago 50 miles of open ocean 1 million aborigines 1788 Growth rate from C14 dates Founder pop.: 1,000 – 3,000 Intentional sea voyage  Invasive species Step 3: Spread Australia – initially along coastlines and rivers Eventually move inland Give up maritime technology Step 4: Increasing population Australia: From 1-3,000 to 1 million in 45,000 years Humans as the ultimate invasive species “Sixth Extinction” Anthropocene Humans Colonize virtually all habitats Apex predators extinct Collapsing biodiversity Culprit: Humans/ Climate change / Both? Thinking of humans as invasive species Invasion biology raises different questions Why did our particular lineage of humans survive? How did last widespread other hominin species go extinct? Neanderthals: 400,000 – 40,000 years ag Homo neanderthalensis (H.n.) – non-human hominin (hominin – grp of modern humans and extinct human species) H.n. similar to Homo sapiens (H.s. - fully-modern humans) Fire Tools Meat eating To some extent: signs / language H.n. contributed to the H.s. genome Neanderthals and “Mousterian” stone tools Mousterian tools made using “Levellois” technique Core prepared by striking flakes from its edges Core's edges trimmed to create a domed shape resembling a turtle shell Core is struck to remove a flake Used as scrapers, knives, or spearpoints Levallois replaced Acheulian technique in Europe  Neanderthals and Homo sapiens H.n. extinction coincides (almost) with two other processes: H. sapiens (i.e. fully-mod humans) arrival in Europe Earliest wolf-dogs (i.e. semi-domesticated wolves) Possible symbiotic relationship b/w H.s. and wolf-dogs (i.e. mutually beneficial relationship b/w species)  Neanderthal DNA H. neanderthal mtDNA Distinct from H. sapiens Divergence from H. sapiens 700,000 ya H. Neanderthal nuclear DNA Overlapped (1-4%) with H. sapiens DNA Confined to modern humans of Euro / Asian decent Interbreeding likely Details of process unclear Neanderthal DNA Separate species: not able to crossbreed and yield fertile offspring Thus, evidence of crossbreeding argues against species-level separation However, only 1 and 4 percent Little substantial biological effect? Neanderthal DNA in modern humans H. n. DNA occurs in genes that affect keratin, protein involved in skin, nails, and hair Genes may have helped modern humans adapt to cold Eurasian climate Genes associated with keratin also help with wound healing H. n. genes also linked to lupus, Crohn’s disease, type 2 diabetes H. s. and H. n. close enough to exchange genes to a limited extent Human Evolution – What’s Next? Archaeology offers a window into past human and hominin behaviors Questions for future research: How do environmental pressures shape species development? What can modern humans learn from the fate of the Neanderthals?