Gaining Insight into Evolution and Natural Selection

[DaveC426913]

Thanks lavinia. Great answers. much food for thought.

houlahound. Agreed. I don;t think dreaming is a survival advantage, I think it's emergent too.

What I was trying to get at is that, for all creatures, no matter how separated in the tree of life, their common ancestor (that little shrew, running between the legs of T. rex) would have had that ability, passing its complex, dreaming brain on to all its descendants. Dreaming is ancient indeed.

 

[mfb]

What I was trying to get at is that, for all creatures, no matter how separated in the tree of life, their common ancestor (that little shrew, running between the legs of T. rex) would have had that ability, passing its complex, dreaming brain on to all its descendants. Dreaming is ancient indeed.

Not necessarily, things can evolve in separate branches of life separately. Eyes are a typical example, they evolved many times (estimates are 40-100) independently.

 

[DaveC426913]

Unlike its sister show, Star Trek, which tried to explain the tech and ended coming up with a lot of BS.

Not necessarily, things can evolve in separate branches of life separately. Eyes are a typical example, they evolved many times (estimates are 40-100) independently.

Yes. Convergent evolution.
Though I suspect in this case, it's really common ancestral trait.

 

[Pythagorean]

Yes. Convergent evolution.
Though I suspect in this case, it's really common ancestral trait.

I always wonder about this. For instance, the bill of birds and the platypus can be said to be a case of convergent evolution. But we're really only talking about macroscopic morphology aren't we? Do alpha and beta keratin ultimately come from the same ancestor and thus share the micro-structural morphology that allowed both animals to grow a bill?

 

[BillTre]

Just found this discussion.

Here are some other things to consider:

1)
There is a lot of genetic information in modern animals (including humans):

• 10⁸ to 10¹¹ base pairs (each a choice of 4 possibilities)
• 10-40,000 protein coding genes
• unknown numbers of other non-protein encoding genetic elements

There's lots of inherited information there. This information is available to each cell in each animal (billions in people) to possibly be used independently.

2)
Many (most?) traits are what I would call generative. They are not encoded directly in the genome. They are assembled during collaborative events during development, usually involving many cells using many sources of genetic information. Each of these cells and genetic factors will have some capabilities and dependencies that are different from other kinds of cells or genetic factors. This kind of stuff is somewhat hidden and not easily observed since it is microscopic and chemical in nature, and is often hidden inside developing eggs or a pregnant mother.

The nervous system and the behavior it generates is like this. Single genes can have an effect but they are embedded within the developing system in which they find themselves (the individual animal). The population’s shared genetic resources will affect the success of a novel gene in such a situation. If a gene is successful in one animal out of a population of a million, but the other animals in the population lack the supporting cast it will not workout well for the gene in the long run, until it can frequently encounter the right supporting cast as it makes its way through the succeeding generations into which it gets bred.

3)
Evolution usually deals with large numbers of individuals combined with many repetitions over time (a multiplicative increase in the number of adaptation tests). Weak traits (small adaptive advantage) can be strongly selected (to achieve high frequency in the population) in larger populations over many generations of time. The many repetitions of the selection process (each short generation) can continuously ratchet up a gene’s frequency as it gradually becomes more widespread in a population.

Cow tail/eyelashes could have a small effect on breeding success in a single generation but over many generations (involving small statistical differences in survival/breeding) can lead to a situation where all animals in a species have a particular trait.

Scenario: Perhaps the longer hairs reduce the likelihood of flies infecting the cows with as many parasites as its shorter haired relatives (or draining them of so much blood), which makes them better able to provide for their offspring, who are then more likely to go on and breed.

I think there are examples similar to this in biological aspects of aquacultural engineering where calories in/health vs. growth/reproductive state are studied quantitatively.

Perhaps the individual vs. the population could be thought of as something like wave and particles.
But wait, there’s more: Another way to think about these things is to consider genes and the selection on them as they get their genetic ride through generations of organisms. This is the idea behind the Richard Dawkins’s 1976 Selfish Gene book (https://en.wikipedia.org/wiki/The_Selfish_Gene).

4)
Dogs:
Hunting dog behavior has been lead people to following view:
Wolves (from which dogs are derived) had well developed hunting skills selected for over probably millions of years. People can along and domesticated dogs evolved. As people started to select dogs for traits that the people found useful, the ancestral wolf traits were modified. The genetic modifications most likely to be randomly generated are those that break things (most mutants people collect in mutant screens are the equivalent of throwing a monkey wrench into the biological mechanism). Different strains of hunting dogs are thought to use the wolf’s basic hunting sequence of actions (which might be: find something, chase it, kill it, and eat it) but different different genetic lines of dogs can have breaks inserted into this behavioral sequence at different places, resulting in different behaviors.

Generally, new traits are considered less likely to randomly evolve. However, given enough time and chances and an environment (as well as a supporting cast of other factors) where it would be adaptive, these kinds of things can pop up.

A recent example of such a mutation might be the cause of the evolution of a smoother gait in horse which arose about 1200 years ago in England and/or Iceland (https://www.sciencemag.org/news/201...asier-ride-horses-evolved-more-1000-years-ago).

I don’t know about the dog digging, but it seems to be something that all dogs do (in my experience). I would therefore think it is a primitive feature, not evolved anew in terriers.It maybe magnified however.

 

[ebos]

This is probably the most important thing on this thread that I hadn't seen discussed in detail. It's called sexual selection and it affects the course of evolution in sometimes unpredictable ways (e.g., peacock's tail). So maybe cows find long eyelashes attractive? Humans seem to, even though it provides no discernible survival advantage to us.

It probably does in the long run. However, it appears that at this moment in time, our sexual selection is questionable.