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Chapter 24 Human Origins
Terms in this set (38)
when did the great ape family free split into humans and chimps?
three ways in which the tree of life can be analyized
comparative anatomy, molecular analysis, and the fossil record
400 species, includes prosimians (lemurs, bush babies), monkeys, and apes
features that distinguish primates from other animals
nails instead of claws, eyes on front of face not sides, form of opposable thumbs
orangutan, gorilla, bonobo, chimp, humans
14 species of gibbon
Mary-Claire King and Allan Wilson DNA study
used DNA molecules of humans and chimps to sequence their genomes which differed by only 1%
all members of the different species in the lineage leading to humans
oldest member of the hominin lineage, found in Chad,
combines modern human features and ancestral features
dated to around 7 mya
chimp sized brain, human brow ridge
Ardipithecus ramidus, Ardi
4.4 mya, Ethiopia
capable of walking upright, using two limbs on ground and four in trees
Australopithecus afarensis, Lucy
3.2 mya, Ethiopia
fully bipedal, less than 4 ft tall, small brain size
habitually walking upright
trends of evolution of hominins over entire record
body size increase, cranium size increase, brain size increase
when did hominins leave africa?
2 mya, homo ergaster (homo erectus) was the first to leave and go to Eurasia - not australia or americas
homo neanderthalensis, neanderthals
600,000 years ago - disappeared 30,000 years ago
fossils first appeared in Europe and Middle East
thicker boned and flatter heads than homo sapiens, slightly larger brains
homo floresiensis, the hobbit
became extinct 12,000 years ago
limited to indonesian island of Flores, 3 ft tall
derived from homo erectus, small because limited food availability
implies that different homo erectus populations throughout the Old World evolved parallel
modern humans evolved convergently in multiple populations around the world
modern humans (homo sapiens) arose recently from homo erectus decedents in africa around 200,000 years ago then moved out
Rebecca Cann from Allen Wilson's lab thought of this
mitochondrial DNA, mtDNA
small circle of DNA, 17,000 bp long found in the mitochondrion
much more abundant than DNA
inherited from your mother in the egg
no opportunity for recombination from sperm, only changes arise from mutation
through mtDNA Cann was able to estimate that the common ancestor of all modern humans lived...
200,000 years ago, human tree is very new
Y chromosome DNA sequencing confirmed that...
the human family is young and arose in africa
excluding homo floresiensis, the last of the nonmodern humans were...
first population of homo sapiens to arrive in Europe, beat out neanderthals
mtDNA, homo sapiens and neanderthals
there is no mtDNA of neanderthals in modern humans: no interbreeding
1-4% of non-african genome is neanderthal: interbreeding
only male neanderthals interbred with modern human ancestors
where did language originate?
anatomical changes due to the shift to bipedalism
foramen magnum moved to the center of skull, spine become S shaped rather than a singular curve, pelvis changed to accommodate longer legs that are directly under the body
why did hominins become bipedal?
made long distance travel easier, freed up their hands
caused specialized hand function to evolve - opposable thumb
lead to tool use
manipulating food lead to evolved jaw
lead to language
where did the most significant evolutionary changes that separate humans and chimps come from?
changes in gene regulation, FOXP2 gene
long-term evolutionary process in which the timing of development is altered so that a sexually mature organism still retains the physical characteristics of the juvenile form
humans have _____ brains in comparison to bod size
3 factors that promoted evolution of large human brain
tool use, social living, language
reorganization of existing structures and pathways is the most important product of the evolution
gene that encodes for transcription factors that play a large role in developement
mutations in this gene cause speech and language disabilities
humans have it but chimps do not
neanderthals have it but a less advanced version which gives evidence to the fact that it arose before neanderthals and modern humans split
two sources of diversity in humans
genetic variation, differences in enviornments
in DNA sequencing ___ in every 1000 bp is different
1, low genetic variation among humans
look different because genome consists of 3 billion bp so that adds up quickly - 3 million bp differences
when did human populations disperse?
60,000 years ago - recently
85% of genetic information is the same in all populations
tall, skinny, dark skinned people are fit for ______ environments.
short, stocky, light skinned people are fit for ______ environments.
malaria and favism (anemia)
S allele helps with the resistance of malaria in africa if heterozygous
G6PD is involved with glucose metabolism and a mutated, heterozygous gene of this helps resist malaria as well
body of learned behaviors that are socially transmitted among individuals and passed down from one generation to the next
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