Flashcards in Topic 2 - Evolution of Humans Deck (62)
how has the earth changed over the past 15 million years?
over the past 15 million years, the earths climate has been cooling with a particularly cold phase c.2.6 Ma called a glacial interspersed with warmer inter-glacial - we are currently in an inter-glacial (holocene)
what forms earths crust?
Earths crust is a patchwork of individual plates that form continents and ocean floors constantly moving relative to one another. they influenced migration and dispersal of plants and animals
what did mountain building effect?
they caused mountain building which has affected atmospheric circulation patterns and majorly effected ocean currents and climate
how are climactic and other environmental changes impact on evolution?
climactic and other environmental changes of the last 70Ma are important driving force in evolution as environmental variability leads to expansion, contraction and fragmentation of habitats
what does habitat change test?
the process of habitat change tests ability of populations to adapt, sometimes resulting in extinction, migration or the emergence of a new species.
what are humans?
Humans are apes belonging to the superfamily Hominoidea along with chimps, gorillas etc. Humans are a special subgroup called Hominins, morphologically and genetically our closest relatives are chimps.
what are the differences between chimps and humans?
the differences between humans and chimps are of degree rather than kind, pelvis, backbone, foot, dentition and brain size and complexity are some of those differences
what characteristics are different in humans and chimps?
they also differ in characteristics, for example hunting is a distinctly human trait.
how do humans and chimps differ genetically?
Apes and humans also differ in their genetic characteristics. we share 98.7% similarity in DNA but differences have arisen through 'point mutations' over time and have accumulated at a known rate. this can be used as a 'molecular clock' to give a measure of the time that has elapsed since the ape-hominin split.
where do genetic and fossil evidence place human origins?
genetic and fossil evidence places human origins in Africa as most fossils are recovered from the East African Rift Valley or South African cave sites.
what has the EARV emerged as?
the EARV has emerged as the result of massive geological faulting coupled with intense volcanic activity resulting in rapid accumulation of sediments bearing extinct animals including hominins that can be dated by radiometric techniques.
what mix do bipedal apes have?
Bipedal apes have a mix of primitive and advanced features. their apelike features include a small brain with large incisors and canines where their homo-like features include being bipedal and the morphology of their pelvis, leg and foramen magnum
when did Australopithecus live?
Australopithecus lived several million years after the evolutionary split predicted by the molecular clock theory. earlier fossils however, are few in number, very fragmentary and provide no conclusive evidence of bipedalism
what emerged after 3Ma?
after 3Ma, 2 forms of Australopith emerged, gracile and robust that had massive jaws and teeth, sagittal crest and zygomatic arches
what were australopithecines adapted for? why were they not classed as the same genome as humans tho?
Australopithecines were adapted for bipedal walking but not sufficiently similar to modern humans to be classed in the same genus due to their ape-sized brains, more 'primitive' dentition's and different morphology of the pelvis and thigh bone
when do the earliest members of the genus Homo appear?
earliest member of genus Homo appear 2.4 million years ago, attributed to genus homo due to their association with stone tools
what was discovered about H. Habilis?
H. Habilis once thought to be the only large brained hominin living in Africa c. 2Ma although reassessment of fossil material discovered that several different forms of early homo co-existed c.2.4-1.4Ma
what has early human behavior been reconstructed from?
early human behavior has been reconstructed from evidence found in 100m thick sequence of lake, river and volcanic deposits at Olduvai
what was found at Olduvai?
here, stone artefacts were found in distinct concentrations, some associating with animal bones leading to 3 broad functional categories, butchering, living and quarry sites.
what were the Olduvai sites originally thought to be?
Olduvai sites originally thought to be evidence of early hunting although now consensus dictates that they were gatherers or scavengers
what was found in sites of China and Indonesia? how do we know?
fossils of H.erectus discovered at sites in China and Indonesia characterised by big brains and modern body proportions
how was expansion into temperate regions facilitated?
expansion into temperate regions was facilitated by advances in technology which appeared in Africa c. 1.5Ma such as bifacial handaxes and cleavers used primarily as butchery tools
where are there finds of Olduvai-style tools?
there are finds of Olduvai style stone tools in Europe - especially Mediterranean Europe although no fossils of H.erectus or H.ergaster have been found making it a hotly debated topic
when do the earliest hominin fossils date to? where were they found?
earliest hominin fossils in Europe found in caves in Spain dated 1.2-1.1Ma by palaeomagnetism, radiometric dating and biostratigraphy
what kind of sites are rare in Europe?
within Europe, sites older than 0.5Ma are rare. one explanation states that sites have not been preserved and early hominin population was very small
what else may have inhibited colonisation in Europe
there was also oscillations of climate that may have resulted in several unsuccessful attempts to colonise Europe
what did the hominins need to colonise Eurasia? what evidence do we have?
Hominins may have needed fire and cooking to colonise Eurasia, burnt materials (ash and bone) was found on sites in Africa back to 1.5Ma although this could be wild fire as there were no recognisable hearths
was early technology confined to stone?
early technology was not confined to stone as wood was used extensively, there are wooden spears belonging to Acheulian time range on several sites in places such as Essex, Slovenia and Germany
when was Europe colonised?
hominins colonised Europe before 1Ma but it was perhaps only extensively settled after 0.5Ma and archaeological remains of the period before 0.3Ma belong to the lower paleolithic