The Curious Case of Homo floresiensis Selection or Pathology Stone Tools and Fossils on East Indonesian Island LB1 A Small Bodied Hominin from Late Pleistocene Age of a New Hominin Why the small size Homo Sapiens Skeletal Remains Brain of LB1 Homo floresiensis Homo florensis Nature 1998 Fission track ages of stone tools and fossils on the east Indonesian island of Flores o Stone tools from 840 000 years ago found in Flores o Flores was not connected to mainland since early Pliocene o Conclusion H erectus was a seafarer who had sailed to the Nature 2004 A new small bodied hominin from the Late Pleistocene of Flores Indonesia island o LB1 Ancestral Traits Small brain size 417 cc Brow ridges No chin Derived traits Nicknamed the Hobbit Small teeth Narrow nasal opening Short face Brain is 1 3 size of modern human brain Only 3 feet tall as an adult Dates to just 60 000 years ago The lower limbs are very short Upper arm humerus is straight rather than twisted Lower arm ulna is short and straight Comparing LB1 to African Pygmy and modern human Letters to Nature 2004 Archaeology and age of a new o Fossils are found in sediments with stone tools hominin from Flores in eastern Indonesia Many look like Oldowan flake tools Some resemble more sophisticated technology o Sediments also contain evidence of butchered stegodons dwarf elephants komodo dragons bats giant rats etc and fire for potentially cooking meat What explains the small size o LB6 o Insular dwarfing the island rule PNAS 2006 Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua Flores Population affinities and pathological abnormalities o Some skeptics argued that LB1 was a recent modern human ancestor of pygmies that still live in the area o Others pointed out that the brain size was even smaller than it should be given the body size o Microcephalic dwarfism a genetic disorder whose victims have small bodies and small brains but sometimes near normal intelligence The Brain of LB1 Homo floresiensis o While the size of the brain is similar to pygmies or o LB1 is not a pygmy or a Microcephalic modern human based microcephalics the shape of the brain is very different on the shape of the brain Nature 2009 Insular dwarfism in hippos and a model for o Brain capacities of an extinct dwarf species of hippo from brain size reduction in Homo floresiensis Madagascar are up to 30 smaller than those of a mainland African ancestor scaled to equivalent body mass o Brain size and body size need not scale linearly during insular dwarfism o The Primitive Wrist of Homo floresiensis and its implications for hominin evolution H floresiensis wrist bones resemble those of an Australopith or a modern ape more closely than those of a modern human Nature 2009 The foot of Homo florensis o The foot looks more like that of a Pliocene australopithecine than a modern human or even H erectus The origin spread of Homo sapiens Paradoxical Mix of Features in Neanderthals Which morphological characteristics mark H Sapiens When and Where did h sapiens first appear How did H sapiens spread throughout the Old World Paradoxical mix of features in Neandertals o Neandertals had big brains but they also had robust bodies o Neandertals were successful hunters yet they had low o Neandertals had diverse tool forms and complex techniques population density and experienced little long term growth of manufacture but technology slow to change and few novel innovations over 250 000 years spiritual life but they never produced a recognizable style or tradition of art o Neandertals may have buried their dead suggesting a Morphological Characteristics that Mark H Sapiens Derived traits of modern Humans Face o Short and flat o Protruding chin o Small brow ridges o Small nose o Non prognathic Small teeth Large brain case o High forehead o Broadest point near top Skeleton o Longer limbs slighter bones o Properties of mtDNA Mitochondrial DNA vs Nuclear DNA Small circular molecules Codes for 37 genes small amount Under very weak selection if any Chance of passing on 0 1 or 2 over generations Many maternal lines starting out only one in the end o Mitochondrial Eve Inherited through maternal line only with no recombination because of drift Eve is the one that persists Despite much larger population size humans display less genetic What does this tell us about the evolution of modern humans diversity than chimps o Low genetic diversity in modern humans suggests that human population expanded quickly from a bottleneck less than 130 kya at about 90 kya o Current geographic pattern of mtDNA haplotypes also helps us reconstruct expansion of modern humans The study Complete mtDNA genome sequences from 277 Patterns of variation in mtDNA haplotypes used to people around world build gene trees The mtDNA gene tree o History of changes in mtDNA haplotypes o Deepest branches most diversity in Africa o Similar haplotypes group geographically Why do African populations show greater within group genetic diversity than other populations o Expectation of genetic diversity due to serial founder effects that accompanied the expansion out of Africa From founder effect of drift in first unit The effect of ancient population bottlenecks on human phenotypic variation o 37 measurements on skulls o 4 666 male skulls date 2 000 years old o 105 populations o within population variance computed o Africa the likely origin of modern humans When and Where H sapiens first appear Oldest fossil remains of H sapiens were found in Ethiopia date to The finds from Herto Ethiopia date to around 160 kya 190kya o H sapiens idaltu fossil evidence of early anatomically modern humans at about 190 and 160 kya in Ethiopia Models for the origin of modern humans 3 common models multiregional continuity all considered to be homo single African origin hypothesis homo sapiens distinct first modern humans from Africa and spread able to sapiens species from Neanderthals interbreed with species that they meet elsewhere combination of the first two theories