evolution Flashcards
what is natural selection?
Darwin’s theory that organisms who are better adapted to changes in the environment are more likely to survive and pass on the useful characteristics to the next generation
what 4 things provide evidence for evolution?
- fossils
- bacteria
- stone tools
- pentadactyl limb
how does bacteria provide evidence of evolution?
- bacteria sometimes develop mutations in their DNA which can create new alleles, changing their characteristics, like becoming resistant to bacteria
- resistant bacteria will survive longer and reproduce more
- allele for antibiotic resistance will be passed on to lots of offspring
- provides evidence for evolution as bacteria become more adapted to environment in which antibiotics exist
how do fossils provide evidence of evolution?
evidence from fossils suggests that humans and chimpanzees evolved from a common ancestor that existed millions of years ago
fossils have characteristics between apes and humans which shows us how humans have evolved over time
what are hominids?
human beings and their ancestors
Ardi
4.4 million years old fossil hominid
- had ape-like big toe, more suited to climbing than walking
- brain very similar in size to chimp’s brain
- long arms and short legs, more ape-like than human
- structure of legs suggested she walked upright
Lucy
3.2 million years old fossil hominid
- leg structure shows she was able to walk upright more efficiently than Ardi
- brain larger than Ardi’s but still similar to chimp’s brain
- arched feet more adapted to walking than climbing
Turkana boy
1.6 million years old fossil hominid
- brain much larger than Ardi and Lucy’s, similar to humans
- shorter arms and longer legs, more human-like
- structure of his legs show he was even better adapted to walking upright than Lucy
who was Darwin?
scientist who came up with the theory of evolution by natural selection
wrote a famous book ‘On the origin of species’ which gave him more fame than Wallace
who was Wallace?
another scientist working at the same time at Darwin, who also came up with natural selection, although both didn’t always agree on mechanisms involved in natural selection
Wallace had lots of evidence to back up the theory, and both scientists published their work together
pentadactyl limb
limb with five digits
how does pentadactyl limb provide evidence for evolution?
pentadactyl limb is present in many species like mammals, reptiles, etc but in different species, it has different functions
similarity in bone structure provides evidence that these species have evolved from a common ancestor which supports Darwin’s theory
how do stone tools provide evidence for evolution?
provides evidence for evolution as stone tools became more complex as the human brain grew bigger
for example, about 3 million years ago, there were a lot of pebble tools, very simple stone stools
however, 200,000 years ago to present day, we now have flint tools, arrowheads, fish hooks, needles etc
how do scientists work out how old stone tools are?
- stratigraphy; study of rock layers, tools or fossils in deeper layers are probably older
- carbon 14 dating; stone tools often found with carbon material
how were organisms classified originally?
according to similarities and differences in their observable characteristics
