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BIO 351 > History of life - Humans > Flashcards

History of life - Humans Flashcards

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Biology 101 flashcards
1
Q

Mammals during Dinasours

A

Mammals hang on in dinosaur dominated ecosystems
- Mostly small BUT some ecological expansion
- Overall = Bog shift in mesazoic (marsupials + placental) THEN diversify in the cretacous

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2
Q

Fossils of Primates

A

Earliest fossil primates appear in Eocene
- Small Aboreal (lived in trees) omnivores
- Not too long after astorid = get primates

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3
Q

Where did primates likely evolve

A

Likley originated in North America and Spread to Europe
- NA = where the earliest fossils are from

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4
Q

Timing of primates

A

Fossils = seen after the cretceous BUT if we look at the molecular clock of the nuetral mutation rate –> the molecular clock puts first primate back to before the atsroid (Suggests older orgin)

Means the orgin of primates = during the cretacous (end of the dinasours)
- Ancestors pop up when have diverisfying of mammals
- All mammals diversify during the cretecous
- All placental mammals alive in the cretecoius –> diverify by the time wipe dinsours out

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5
Q

Primate family Tree

A

Colugos split – split from our closest living order (Dermopetra)
- Split from Cologous in cretecous
- Colugos = closte living relatoives to primates

lemurs and Galagos – Protsimeans –> primates split form them in the cretecous (split from prosimians)
- Before the dinasours dies = have diversofications
- Last common ancestor of all extent primated = 69 MYA
- No fossil evidence in this time frame

Split between Tarsiers + Monkeys and apes
- Start having fossils (evidence is consistent with mol. data) – have ancetsors of two distict lineages with tarsiers splitting from what would become mokeys and apes

Split new world monkeys and old world monkeys
- We are old world monkeys
- New world vs. old world = difereny nose strocture + tails + Dentition + Claws
- Have fossils and molecular data match – have monkeys from Africa going to South America (Primates and rodents went to South America fatser than others)

THEN CA of old world and Apes/humans
- We are in clade in Apes
- Old world show up 30 MYA and by 25 MYA have divergence from lineage of Mokeys
- We are in Catahinni – Old world + Apes

THEN great apes split from gibbons
- Fossil evidence of gibbon evolution is scant but we know that they had rapid radiation in SE asia (18 species in 4 genera)

THEN Orangutangs split – Ancestral form of apes were commin in Euprope at the time
- Orangtagne ancestors show up in middle eat/India and move eastward into east asia

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6
Q

Timing of primate diversification evidence

A

Timing is based on molecular clock – no fossils for some of it

BUT the fossils that we do have is consistent with clock

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7
Q

Evidence of tarsiers and Monkey split

A

Not details fossils because they live in forest
- Chance that decompose or picked apart before fossilize

Fossilize differeley in different ecosystems

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8
Q

How did old world monkeys go to South America

A

World was different

NOW – SA vs. Africa –> 2000 miles

Before – SA vs. Africa –> 1000 Km
- Lot closer (Still far)

Way it happens = ocean dispersal

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9
Q

Ocean Disperal

A

rare but happens – it has been obsvered in recent times (often following large stroms or tsunamis)

Overall – Float on a log

Example - Anguini –> colonize by Iguana – got there by drifting on a log from hurricane – 250 km across ocean then colnize island

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10
Q

New worl vs. Old world mokeys

A

They are very divergent – Major synamptomorphes

New = tails + claws not fingernails + nostils on side

Old = Nostils down

Divergent for 40 Million years = different structrually

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11
Q

New worl vs. Old world mokeys

A

They are very divergent – Major synamptomorphes

New = tails + claws not fingernails + nostils on side

Old = Nostils down

Divergent for 40 Million years = different structrually

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12
Q

Diveristy of Gibbons

A

Very diverse 18 spoecies across 4 genera

BUT the diversity occured recentley – involoved a lot of scrambling of the genome –> recent burst od diverity + lots of genome evolution

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13
Q

Humans + Organgutags

A

We are closer to organguates than Gibbons but not much closer than gibbons –> split of organgtags happens in Europe bevcause that is were most early apes are found
- Included large primates

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14
Q

African Apes + Humans

A

African age are much more closley related to us

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15
Q

Humans + old world mokeys

A

We are in clade with old world BUT old world mokeys are also in their own clade – we are sisters

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16
Q

Who are our closets living relatives

A

Based on morpholgy it was hard to know for certain

Molecular and fossil evidence are clear –> NOW know that our closest relatives = Pan (Chimps + Banboes) – closer than gorillas
- Share a common ancestor more recentley with pan than gorilla

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17
Q

Why didn’t we know who humans were closest to?

A

Didn’t know because of issue with phylogenies

DNA based phylogeny does anlways give us the right answer
- Way that some alleles are related might not reflect how species are related

Issues

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18
Q

Issues in Phylogenies

A
  1. Can have too much evolution
    • means relationship is just a coincidence
    • Looks like relationship but it is convergent evolution (homoplasies)
    • Homoplasies resulting from accumulation of independentley derived shared mutations
  2. Have good species but not enough molecular evolution to make gene trees to make species tree
    • Not enough apparent conflicting data
    • result = Incomplete lineage sorting –> Which alleles end in which species might not dictate relationsgip of genes – cause phylogenies to give the wrong answer
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19
Q

Incomplete lineage sorting

A

Variation Present within ancestral population (before speciation) segregates differently among ancestors and diffrent loci

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20
Q

Example of incomplete lineage sorting

A

Start: Have relataive amount of genes diversifying – different segerate during evolution of popultion
- Genes = homologs
- See ancestral relationship –> split wats varaition plays out lragley end up with trees mismatching between species trees

Have 3 allees on one side and three alleas on the other side
- Based on driect evolution alalles on one side and lose allels on yje otehr = different set of alleles on either side of split
- Alleles go to fixaton (have succesive rounds of split them drift)
- Ways it alleles can go to fixation = gives different relatedness to each other when make phylogeney

OVERALL - Have 6 alleles in the ancetsrla na dthe 6 can split into two groups of three and which of the three go to fixation affects the tree and depending on which goes to fixations gives a different phylogeney = gives different relatedness

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21
Q

Bearing careful with DNA evidence

A

Need to be wearying because of Incomplete lineage sorting – be carefuol when making assumption of DNA eviudence
- Can’t rely on it by itself

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22
Q

What compleicates phylogeney more

A

More complicated if add hybridization + migration among diverging popultions
- Further lowers ability to make strong inferences

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23
Q

Diversifcation in our lineage

A

Based on sequences from extant primates - our lineage looks sleepy

Banoes and chimapnees = have a lot of diversiofication that dates back

BUT humans –> diversity seems to be recent

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24
Q

Portryal of lineage

A

For a long time our lineage was portrayed as a straight shot with fossils placed in a linear sequence
- Process of apes to huymans = direct line

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25
Q

Two models of evolution of lineage

A
  1. Progressive evolution of a single lineage
    • One lineage with smooth transition
  2. Evolutionary radiation
    • Adaptive radiation – diversiftcaion of ancestors
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26
Q

Basis for Hypothesis for human evolution in past

A

A lot of hypothesis were soley based on fossils avalble at the time (based on data they had - not a lot)

Members of the genes homo Neaderthals and Homo erectus were discovered early in far flung regions – early man showing up in very different places

There were no fossils filling the gaps between fossil apes and early humans

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27
Q

First fossils of humans

A

First fossils of human like animals = found in 19th century –> hard to place in tree of life

THEn found fossils of neathderals in Europe

THEN found early divergence organism (Homo Erectus) in Java in Africa
- Ancient human in very different part of the world

28
Q

Hypothesis for human evolution in past

A

One of the first hypothesis was that the early humans evoloved completley independentley form local primate popultions
- Earliest version of the Multi regional hypothesis (implies much deeper divergence than any modern form of the hypothesis)

29
Q

Multi regional hypothesis

A

Because we only had a small amount of information from different regions that was hard to tie together –> led people to think that human popultions evolved independently from primate popultions
- Earliest version inplied deeper divergence between modern human popultions
- Fell out of favor when have more fossils (refuted easily)

30
Q

perpetuating Multiregional hypothesis

A

Hypothesis stayed longer than should have

To perpetuate – led to fraud trying to show intermediate ape/human forms were regionally specific
- PLanted skull in England
- Prop up racist narritive

31
Q

Refuting multi regional hypothesis

A

Disciveries in the 20th centruy strongly refute the old racist multiregional hypothesis
- Once found fossils that show action of evolution in east and south Africa

Example - Taung child (Austrolipithocus Africanus) – child that had a mic of ancestrak and derived (human and ape) features
- Evidence from split with humans and chimps
- Found more in the same place

32
Q

Finding new fossils

A

Once reserachers knew were to look –> get fossils + picture of early hominids
- Discoveries began to happen rapidly + continue to this day
- Builds a much more complete picture of doveristy and evolution of early homonids

33
Q

Example fossil #1

A

Lucy (most famous) - Austrralipithicus Afarensis
- Showed that bipedilsim outdated brain size
- One of the most complete skelotons that we have

34
Q

Major questions when finding fossils

A

Which human like attributes arose first
- What traits that seperate us from chimps evoloved first

Question: Did brain or bipedilism evolove first

35
Q

Which huamn attributes arose first

A

Lucy = shows bipedalism outdated brain size

Lucy = has a small brain BUT is bidepal = bipdeal was first before brain got bigger

36
Q

Genus Australopithicus

A

In the genis Austrolo[ithicus – we see clear evidence of transition from ape like to human like features
- Member of genus did well for a while (survived well + diversified for 2 MY)

More recent finds push back closer to ancestor with chimps

37
Q

Potential precusor to Australopithicus

A

Sahelanthropus – date to the split with chimps

***Single skull –> Suggestive of shift towards bipedilism very early
- Skull = indicative of shift to bipedislsm
- Ancestor of chimp might be more bipedal than now

38
Q

Skull + bipedalism

A

Skull = can tell stature of organisms
- Shoulder can tell us about bipedilsm

Where brain stem comes out of = can tell if bipedal or not
- Straight in human because stand straight
- bend in chimps because bent
- Sahelanthropus = in the middle

39
Q

Oldest studied huminand precusore

A

Ardipithecus
- Supright posture BUT still partially adpated to climbing
- Fits almost perfectley with expectations of transtional fossils
- Leg firsts then upper body adapts

40
Q

Australopithecus

A

Species in genus = Fullt upright bipedal homins with small brains
- Might be the first to leave Africa
- Didn’t persisnt or diverisfy much
- Seems to have well throughout Africa

Height of period = diversifying ecologically

41
Q

Split in Australopithecus

A

A diveristy of Australopithecus forms arise but the direct relationships are poorly understood

Australopithecus gave rise to another “robust” Australopithecus lineage – gave rise to Paranthropus
- Early homonins – feature transition from split in Australopithecus
- See Gracile vs. robust forms
- Seen in skeltons + refelcted of ecological diversoty

42
Q

Paranthropus

A

Split from austrolopithecines
- rebust form
- Herbavors – bigger Jaws
- Out last austrolopithecines –> live alongside for a while

43
Q

Split of austrolopithecines and Paranthropus

A

Could show ecoligical speciation – example of ecological diverignece
- Paranthropus dievrsified to specialuze that plays a role in history

44
Q

Example of ecological diverogence

A

Paranthropus filled a new niche feeding on heavy harder to digest plant material

they evoloved alongside our own lineage until 1 MYA

45
Q

Three lineages

A

2 MYA - East Africa contained 3 genera of homonins (Australopithecus,
Paranthropus, and Homo)

46
Q

When for humans appear

A

Organisms that we start refering to as humans appear 2.1 MYA - Homo habalis
- Appearance corresponds to a new kind of trace fossil

Coresponds with tools – when have own genus we also have huge axes in high qunataties
- As soon as we found how to make = made a lot
- Tools might have occured earlier and maybe in a different lineage – more doverse than today

47
Q

Homo habilis

A

Early humans (own genus)
- Emergued in Autropolithiscus –> one diversifed –> led to own sub lineage

48
Q

Tranistion in Homo

A

As soon as homo genus is on scence = start to diverosfy

49
Q

Tools

A

Some recent evenidnece suggest homonins were manipulating stone as far back as 3 Milliob years

Oldest technology - course but consuistent with chopping implements

Likeley birdge from late Austrolopithicus to early Homo

50
Q

Diversification of Homo

A

As soon as the genus homo appears it diversifies and migrates rapidly

51
Q

Homo habilis vs. Homo Rudplphenis

A

Homo habilis was contemporary with Homo rudolphensis - these two seem to show a subtler version of the ”gracile vs robust” ecological divergence in Paranthropus
- Both = confined to Africa
- Again can show ecological sepciation

Paranthrpus + Autsrolopithucus + Homo habilis and Homo Rud = all exist at the same time

52
Q

Moving out of Africs

A

The next phases of evolution sees the first definitive movemnet of our genus out of Africa

Homo Erectus – immediatley show up around the globe
- Depend on Paranthrpolus

53
Q

First species to leave Africa

A

Homo Erecutus – very fast

End all over the world – got to Java + Europe + don’t know how far up in Asia

Creates the second version of Multi regional Hypothesis

54
Q

2nd version of multi regional hypothesis

A

If Homo erectus spread – humans could be indepentley transtional in different regions

European evoloved from Erurope erectus vs. Asia evoloved from erectus in asia

Question: have erectus that might have evoloved once OR mutliple times around the world – did modern humans evolive in one location and subsequnetley disoplace or evolove independentley

55
Q

Question from H. Erectus

A

If Homo erectus occured around the world so early,
did modern human evolve gradually from these populations in each different region? Or did modern humans evolve in one location and subsequently displace H.erectus?

56
Q

Two hypothesis about H. Erectus

A

Hypothesis = make tesble predictions

  1. Humans evoloved early BUT evoloved once in Africa then spread and replaced erectus
    • Erectus divrisfies into different leaines in different locations but H.Sapiens orgionate in africa and then displace the rest
  2. Multiple related errectus spread aorund the wrold then huamns evoloved individually through time
    • Erectus spread across the globe and H.sapiens appear gradially in different regions
57
Q

Answer to evolution from H.Erectus

A

DNA sequencing stronly support a single African Orgin of H.Sapiens
- Multiple fossils shows that the Multiregional hypothesis is incorrect
- Have some gene flow in other H.Erectus popultions BUT anatomical humans evoloved once in Africa
- H.Erectus did diverisfy in other places but are not the orgin of antomical modern humans

58
Q

Common ancestor of all modern humans

A

Common ancetsors of all modern humans likley lived in East Africa 150,000 - 200,000 YA

Anotomical humans go back earlier (300,000 YA - around at least 250,000 YA)

59
Q

Human fossils

A

Earliest fossils of anatomically modern humans appear 200,000 in Ethiopia (now perhaps 300,000 in Morocco)

  • Humans leave Africa in at least a few waves, starting perhaps ~150,000 or more
  • Ancestors of current non-African human populations leave Africa~80,000-60,000 years ago and eventually replace all the other members of the genus that existed at the time
60
Q

Most of Human history

A

For most of our history, we shared the planet with the diverse results of the Homo adaptive radiation

61
Q

Most recent ancestor of Anotomical huamans

A

Most recent CA of modern humans at 200,00 YA

Most recent CA of all Non-african humans = 60-80,000 YA because when groups left Afrcai they displaced H.Erectus

62
Q

Exodus out of Africa

A

Exodus out of Africa 1.9 MYA but out own species didm’t leave until 60-50,000 YA
- In Australia by 60,000 YA
- Went over land bridge to NA less than 20,000 YA

When left they dispalced other popultions along the way
- Co-exist with Neanderthals + Others + H.Erectus –> THEn drove to extiction
- Philipines also had other species and humans displaced them

63
Q

Most of time huamns were around

A

Most of time we were aorund were not the only humans on earth
- For most of time = shared with other huamams that adptivley radaited –> NOT a straight line
- Diversification – Lineage = kess evolution than today

64
Q

What triggered diversifications

A

Could be things that made us more successful – maybe outside resources or extewrnal event

The earth was constintley changing
- Start we had grass land + violcansims –> had lots of oselation of earth’s climate
- Shift = change in landscape = cgange in popultion –> ALSO split popultion (across ice sheets) = create speciation
- Sucess could be traits or could because vecause in the right place when earlth was primed for making diveristy

65
Q

Why are we the ones left

A

Don’t know the answer

Other species make+ use tools

BUT when have humans = start to get cultural artificats different from other groups
- Creative is only in humans

Example - cave with paintings = only in humans
- Also have pottery + scultures + Safisticated tools = only in humans –> other groups didnt have aspect of culture

See human culture + way to interact with eachother = allows us to succeed

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