Flashcards in Evolution and the human story Deck (51):
What did Tinbergens 4 questions consist of?
Which 4 mechanisms explain how evolution works?
Small changes in allele frequencies within a population or species. Can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next.
The sum of long periods of micro-evolution - large changes at or above the level of species.
Define Genetic Drift.
Chance event causes a change in the frequency of alleles in a population. See a drift in the frequency of these alleles over time.
Introduction of variant alleles to a population via a change in the genetic material of the reproductive cell.
Name three types of selection.
Similarity due to descent. -shared ancestry between a pair of structures. For example Mammalian forelimbs.
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon.
e.g. fire has only been used in one lineage.
Characters that do not fit perfectly on a tree. A character shared by a set of species but not present in their common ancestor. For example the wing of a bird and a bat - originated independently. When this happens it is sometimes called convergent evolution.
What does a node represent?
An actual biological population in the past. A speciation event in which two different lineages leading to two different taxa split off.
The relationship between all organisms.
What was milestone 1 in evolution and what evidence do we have of this?
Walking upright - bipedalism.
"Lucy" - 3.2 Mya - Afarensis.
"Ardi" - 4.4 Mya - Ardipithecus Ramidus
-Around 3.8 May bipedalism arising.
What was milestone 2 in evolution ?
Stone tool manufacture - Metatool manufacture using one tool to make another.
Emerged about 2.9 Mya.
Used by Homo Habilis. Simple modification.
What was milestone 3 in evolution?
Use of fire.
What was milestone 4 in evolution?
Big game hunting (coordination/cooperation.)
About 400 kya.
What was milestone 5 in evolution?
Blombos cave in south africa. - Shells with special grooves. Man-made holes, signs of ochre pigment and prolonged wear.
What was milestone 6 in evolution?
Clothing. The first tailored clothing was close-fitting enough to lead to body louse.
What was milestone 7 in evolution?
Ritual burial. Seems clear that bodies had been treated after death.
What was milestone 8 in evolution?
Art - a deliberate will to produce a complex abstract design. Indicates a cultural tradition of creating meaningful symbolic geometric designs.
What was milestone 9 in evolution?
Music. Stone flute found in germany. Lots of craftsmanship has gone into this.
What is symbolic culture?
Meaning attached to arbitrary objects and behaviours due to collective belief in group that symbol is important.
What are the two general trends in evolution?
Brain capacity has increased over time.
Tool use- trend towards lighter, cutting edges for greater efficiency.
Which of tinbergens four questions are dynamic and proximate?
What is a dynamic meaning?
Past explains present.
What is a proximate meaning?
How does X function
What is an ultimate explanation?
Why did X evolve the way it did.
What is a static explanation ?
Explains current form.
Mechanism/causation is what type of explanation?
Proximate and static.
Function is what type of explanation?
Ultimate and static.
Phylogeny is what type of explanation?
Ultimate and Dynamic.
Selection is the only process capable of what?
Not the only driver of change, but the only process capable of generating complex adaptations which can greatly increase the chance of an individual passing on their genes to the next generation.
what was the Scala nature?
Scala naturae – aristotle ranked animals in terms of their complexity. Idea of a natural hierarchy.
A phylogenetic tree represents?
Trees show the evolutionary relationship between the species at the tips. - Read a tree as a set of hierarchically nested groups which are called clades.
What does relatedness refer to?
Time since common ancestry: the more recently species shared a common ancestor, the more related they are.
What do nodes represent?
Actual biological populations in the past. E.g. a primate that lived 6-10 million years ago which was the ancestor of both chimps and humans.
Represents a speciation event - splitting into two different lineages leading to two different taxa.
What does a branch on the phylogenetic tree represent?
Represents a population evolving through time.
What do roots on a phylogenetic tree represent?
Common ancestor of the entire group.
What does a shortened branch on the phylogenetic tree represent?
An extinct species.
What do phylogenetic trees tell us about the scala naturae?
there is no implied improvement in evolution. All species are equally evolved to survive in their own environment.
characters that don’t fit perfectly on a tree. E.g. appears 2+ on a tree. Bird and Bat wings evolved so far about in time, yet structures look so similar. This could happen trhough convergent evolution.
similar form via convertgen or parrallel evolution e.g. streamlined body shape or smoot skin. Because subject to similar selection pressures.
What does phylogenetics teach us?
The relationship between all organisms.
When organisms split from one another.
There is no scala naturae.
How character states have evolved (Homology etc.)
Describe milestone 1:
• Fossil evidence
• “Lucy” (3.2 Mya) – Australopithecus afarensis
• “Ardi” (4.4 Mya) – Ardipithecus ramidus. – adapted for climbing (longer pelvis) and walking. Suggests that ardi evolved in a woodlands. Which went against the idea that bipedalism evolved due to drying out of the environment and adapting to walking over lands and looking out for predators. Key to this is that the story is always changing. However, maybe ardi was not even part of the human lineage.
• Habitually bipedal
• Around 3.8 MYA bipedalism arising.
Describe milestone 2:
Stone tool manufacture.
• Oldowan, named after Olduvai Gorge, Tanzania.
• 2.5 million years ago.
• Homo habilis.
• Simple modification
• No species had ever done anything like this before – usually used teeth and claws. This was a large revolution in terms of technology. Made by hitting one pebble into another. Can make chopper tools or flakes.
• Emerged around 2.9 MYA.
• Food processing and cutting.
Describe milestone 3.
Traces of numerous hearths dating to between 690,000 and 790,000 years ago. – large gap between 2.9 MYA for tools and this.
• Isolated clusters of burned flint, as if toolmakers had been knapping hand axes by several firesides. Making tools and the flint is falling off and going into the fire.
• Fragments of burned fruit, grain and wood scattered about.
Describe milestone 4.
Big game cooperative hunting. • See evidence of prime-dominant mortality from 400 kya.
• See evidence of transportation of high quality parts of animal to cave
- Fallow deer
- Steppe rhino.
Describe milestone 5:
Jewellery.• Grotte des Pigeons at Taforalt, Morocco: find Nassarius gibbosulus 110000 years ago.
• Blombos cave in south Africa: 41 Nassarius shell beads dated to 72,000 years ago. What makes the sholls special is that you can see the grooves that have been made in the shells.
• Man made holes, signs of ochre pigment (ochre is a type of dye that is able to stain objects) and prolonged wear
• Ornaments potentially have social function, such as transmitting meaning to others, conveying an image of you that is not just your biological self.
• Bird claw jewellery in Neanderthals. Neantherals in france and italy regularu used terminal phalanges of bird of prey during the middle Paleolithic. This shows possibbility that some articats may have actually been produced by other species – more to the story. Maybe neanderthals also had jewellery.
Describe milestone 6
• The first tailored clothing was close-fitting enough to lead the head louse to expand its territory.
• A new variety, the body louse evolved 72,000 ± 42,000 years ago with claws adapted for clinging to fabric, not hairs.
• Loose garments like animal skin cloaks likely worn for a long time before. Kittler et al, 2003.
• Possiblity of trading and culture linkages between Morocco and Africa.
Describe milestone 7:
- Seems clear that bodies had been treated after death. Buried with parts of other animals. Maybe something like religion.