human evolution - unit 4 AOS 2

Question 1

humas species name

Answer 1

homo sapiens

Question 2

mammals

Answer 2

• mammals a group of animals that
  are characterised by the presence
  of fur or hair and milk-producing
  mammary glands

Question 3

characteristics of mammals

Answer 3

• milk producing mammory glands
• fur coating body
• varety of teeth

Question 4

primates

Answer 4

• the highest order of mammals, comprised of about 400 different living species who share a number of features including opposable digits and binocular vision

Question 5

characteristics of primates

Answer 5

• binocular vision
• opposable thumbs
• flat nails
• rotating shoulder joints

Question 6

hominoids

Answer 6

• a superfamily of primates that lack a prehensile tail, including apes and humans

Question 7

characteristics of hominoids

Answer 7

• absence of tail
• larger brains
• long upper limbs
• flatter face

Question 8

hominins

Answer 8

• modern human species and our extinct close relatives that could walk with a bipedal locomotion

Question 9

characteristics of hominins

Answer 9

• bipedalism
• large brain
• communication and formation of complex social groups
• use of tools

Question 10

human evolution

Answer 10

• A hominin is any species, living or dead, that can be classified in the taxonomic tribe Hominini. This includes modern humans, as well as our upright-walking ancestors, such as those from the genera Homo and Australopithecus.

Question 11

Australopithecus to homo

Answer 11

Australopithecus anamensis
Australopithecus afarensis
Australopithecus africanus
Australopithecus sediba

Homo habilis
Homo erectus
Homo neanderthalensis
Homo sapiens

Question 12

trends in human evolution - brain size

Answer 12

• brain size has increases
• this is evidenced by larger cranium fossils

Question 13

trends in human evolution - limb size and shape

Answer 13

• larger legs in proportion to arms
• femur and tibia join at an angle
• pelvis wider and more bowl shaped
• larger heels, longer feet and more prominant arch
• more cental foraman magnum
• less prominent brow ridge

Question 14

why the human fossil record is open to interpretations

Answer 14

the record itself is not complete
- very few human fossils have been found

Not all individuals die in conditions that promote fossilisation.
- For example, organisms might decompose completely or be eaten by scavengers when they die.
- many homanin species only existed for a short period of time
- burrial rituals and not leaving dead behind
- Many rock layers are still inaccessible to paleontologists, so not all fossils have been found.

• Each discovery of a fossil hominin may provide new information that can be used to test currently accepted hypotheses. Often this results in clarification and increased understanding of hominin evolution
• evidence form DNA is often incomplete
• Classification schemes are not fixed but may change when new information becomes available or when new interpretations that provide better explanations are formulated.

Question 15

humans interbreeding with Neanderthals

Answer 15

• humans interbred with the Neanderthals, a completely different species – 50 000 years ago.
• H. neanderthalensis and H. sapiens are not directly related, but rather they share a common
  ancestor.
• Neanderthals diverged from a species that later gave rise to home sapiens.

evidence of interbreeding
- they coexisted at the same time in the same locations
- comparison of genomes confirm that Modern humans today have some neanderthal DNA
- some of the mtDNA in found in neanderthal fossils aligns with that of modern humans
- This finding provides evidence that, after leaving Africa, modern humans interbred with Neanderthals, which is why many modern africans do not contain neanderthal DNA.

Question 16

new homo species

Answer 16

• Specifically, new putative Homo species are constantly being discovered and are leading to
  contestation of our current classification scheme, leading to new interpretations.
• even completely new classifications
• Homo denisovans were identifies based on mtDNA
• DNA evidence indicates Homo denisovans is most closely related to Neanderthals

Question 17

out of Africa hypothesis

Answer 17

• This hypothesis suggests that Homo sapiens evolved in Africa around 200 000 to 300 000 years ago, long after the departure of Homo erectus into Eurasia, and remained there for an extended period of time (around 100 000 years) before emigrating in waves and replacing existing hominin species such as Homo erectus and Homo neanderthalensis in different parts of Europe and Asia about 150 000 years ago

Question 18

evidence of out of africa

Answer 18

• mtDNA can be used to trace back linages to a common ancestor in Africa
• modern humans show very little genetic diversity compare to Africans. this suggests that Africa was the source populations and that non africans show a subset of this diversity
• Genetic studies have shown that modern humans outside Africa have small amounts of Neanderthal and Denisovan DNA, but African populations do not. This supports the idea that Homo sapiens migrated out of Africa and encountered (and interbred with) these other hominin species after leaving Africa.
• oldest fossils are found inside of africa and fossils out of africa are younger suggesting modern humans migrated out of africa

Question 19

Multiregional hypothesis

Answer 19

• This hypothesis suggests that the evolution of modern humans, from Homo erectus to Homo
  sapiens, was actually an ongoing process across all regions of the world with gene flow between different continental populations. In other words, the multiregional model posits that Homo sapiens evolved from several different geographically separate groups of Homo erectus who had migrated across much of Africa and Eurasia in the million years prior to the emergence of modern humans

Question 20

Aboriginal and torres strait islander people

Answer 20

• In other words, Indigenous Australian people are the longest surviving population of modern humans to have lived in a given location, and are thought to have one of the strongest Connection to Country of
  any living population on earth.

Question 21

mtDNA

Answer 21

mtDNA: DNA that is only inherited from the mother
- no recombination: mtDNA is passed down to offspring and does not undergo recombination meaning it remains relatively unchanged from generation to generation. This allows researchers to follow maternal lineages and study how populations have migrated and evolved over time.
- higher mutation rate, allowing scientists to look at how populations have diverged and migrated over time
- less DNA so faster to sequence

disadvantages:
- only inherited from mother and so cannot track paternal linages
- does not provide evidence for interbreeding
- lack of recombination and genetic diversity can make it difficult to detect differences between populations

Question 22

whole genome DNA

Answer 22

whole genome DNA
- inherited from both parents so provides evidence of maternal and paternal linages
- recombination
- less mutation rate
- provides information about interbreeding.

advantages
- more bases so more information available
- can be used to determine interbreeding
- information about inherited mutations
- lower mutation rate because of repair mechanisms

Question 23

evidence of hominin existence

Answer 23

• fires
• stone tools
• cave paintings
• human fossils

Question 24

evidence of human migration

Answer 24

• more genetic diversity in Africa that other parts of the word, suggesting that homo sapiens evolved there and then migrated across the world
• fossil evidence shows that the oldest fossils originate from Africa whereas fossils outside of Africa were younger, suggesting homo sapiens migrated out of Africa
• mitochondrial DNA: mutations create distinct genetic lineages, known as haplogroups. Each haplogroup represents significant differences in matrilineal mitochondrial DNA and allows for the migration of human populations tobe tracked out of Africa. Each haplogroup can be traced back to a common maternal ancestor and specific geographic regions