Vrbic said:
b) The evolution causes the pressure of the environs.
If by "causes the pressure of the environs", you mean effecting in some manner, changes in the environment;
Then, the relationship between evolving organisms and the environment to a two way thing.
There are clear cases of biology having big influences on the environment.
One of the largest effects is the
oxygenation of the atmosphere.
First there was no oxygen, then biology started producing oxygen.
Iron in the oceans oxidized and fell out of solution in the oceans (big effect).
Further oxygenation eventually increased atmospheric oxygen levels. It also affected weathering of rocks.
As a result of an oxygenated atmosphere, the biological environment was changed.
This oxygenated atmosphere had effects on the biological entities in many environments (going in environment to biology now).
Most anaerobes did not do well in an oxygenated environment and had to find (in a non-anthropomorphic way) oxygen lacking refuges in which to live.
Aerobic organisms evolved to take advantage of the increased oxygen availability in the new environment.
Vrbic said:
c) Dinosaurs didn't develop into intelligent creatures, because they were dominant (some were big, some were quick,...) in their environment. There wasn't any significant ambient pressure for that.
I don't buy the part in red. Here is way:
Being dominant (to me, in the context of evolution) means being successful in the evolutionary processes (survival and reproduction of individuals, persistence of species, and in evolving of new species from pre-existing ones (this would be speciation)).
Largeness might be an evolutionary trap, more difficult to get out of.
Important to any argument about dinosaurs, is that they evolved many species with lots variations on their body plans.
Their dominance was not necessarily a hindrance to evolving intelligence.
however, the lacking of "significant ambient pressure" might reduce or eliminate any selection for higher intelligence.
Lacking other things and conditions that would be required to evolve intelligence has also been argued (see below).
If being dominant is being large, then the arguments might be different.
Vrbic said:
Why didn't any smaller dinosaur or not dominant animal developed into the intelligent being?
Although there were
small dinosaurs, they would have had the same problem generally as any others which could easily have been the same as above:
the lacking of "significant ambient pressure" might reduce or eliminate any selection for higher intelligence.
There were also small mammals around with the dinosaurs. They eventually evolved into people with intelligence. However, it took millions of years of evolutionary set-up time to generate the animals that eventually evolved into people. At the time of the dinosaurs, presumably, they also lacked
"significant ambient pressure" might reduce or eliminate any selection for higher intelligence.
Lacking of other biological parts and/or conditions that might be required to evolve intelligence can also be argued.
The required parts/conditions class of explanations which involve arguments about how the dinosaurs might be
lacking one or more critical traits, preventing them from being able to put together all the biological parts to achieve intelligence.
These might include:
- brain size
- brain structure
- developmental processes underlying brain/body structures
- an intellectually challenging environment (living in trees (complex 3-D environment) prior to evolving humans) that might favor increased computational abilities.
- environmental changes (such as forests --> grasslands) where intelligence could be useful because it can change faster than biology evolves (and therefore adaptive).
This is a more theoretical and conjectural view.
Vrbic said:
2) What caused the human developed into an intelligent being?
Controversial, with no common conclusion at this time.
Many possible factors.
russ_watters said:
To restate, the thing to understand is that other than complexity, evolution does not have a specific "direction".
Things are more complex than this.
There are certainly many highly complex organisms.
And evolution certainly increased complexity from its low complexity beginnings when the non-living whatever-they-were's that life evolved from (going from a non-self-sustaining level of complexity to the (presumably) much higher levels of complexity found in today's self-sustaining biological organisms).
However, there are many well known examples of evolution going in the direction of reduced complexity. Therefore the general statement is wrong.
Wikipedia biol complexity article here.
Parasites provide many common examples of structurally simplified organisms (although they may evolve more elaborate life cycles).
From a
wikipedia article on parasites:
Trait loss
Parasites can exploit their hosts to carry out a number of functions that they would otherwise have to carry out for themselves. Parasites which lose those functions then have a selective advantage, as they can divert resources to reproduction. Many insect ectoparasites including
bedbugs,
batbugs,
lice and
fleas have lost their
ability to fly, relying instead on their hosts for transport.
[88] Trait loss more generally is widespread among parasites.
[89]
This can even go as far as
Giardia, which is a eukaryotic intestinal parasite that has lost its
mitochondrial function.
Mitochondria themselves are examples of complexity reductions in evolution. But perhaps not depending on point of view (how analyzed).
The standard story would be something like:
A bacteria takes up residence inside of an archaeal cell (similar to bacterial cells in many ways),
The bacteria evolves into the
mitochondria. Its get what it needs from its host archaeal cell and gives back ATP,
The
mitochondria's genome has thrown away almost all of a typical bacteria's genes.
Going from the 1,500 to 2,000 genes in many bacteria,
mitochondria have:
The number of
mitochondrial protein genes varies from 3 to 67, while tRNA gene content varies from 0 to 27.
according to
this article.
This is the "higher" and more complex eukaryotic cell.
It can be seen as both a complexity decrease (individual
mitochondria) and as an increase (from a bacteria and archaeal cell to a eukaryotic cell).
The archeal cell has formed a much enlarged eukaryotic cell body (based on energy from the
mitochondria), has a relatively huge genome that encodes to production of many different highly specialized proteins and larger structures.
A eukaryotic cell can contain hundreds or thousands of individual
mitochondria (each with a tiny little genome).
There is complex decision to be made on how balance the complexities of the
mitochondrial (and the many copies of the
mitochondria/cell) and the eukaryotic cell of which it is a significant part, if you want to consider the problem from that point of view.
Another way to consider evolution might be the changes in ecosystems (a different kind of biological entity) over time.
Ecosystems are more complex than when there were none (pre-biology).
There are a lot of complex ecosystems.
However, ecosystems can also go in a path toward reduced complexity.
Changing climatic conditions (no rainfall?
desertification), invasive species (
Caulerpa in the Mediterranean), or
loss of a top predator can result in an ecosystem "reduction" (usually thought of as number of species; sometimes as capture, by the biology, of energy going through the environment).
