So if it survives it's fit, if it's fit it survives? The old tautology

▲ pegasus 10 minutes ago | parent | next [-]

Evolution is survival of the fittest. That's not a tautology, it actually says something, namely that the traits which survive and thus propagate tend to be the ones that enable some form of adaptation to its living conditions to the individual. The paper lists a bunch of examples:

  - lactose tolerance
  - immunity and disease resistance
  - lighter skin at northern latitudes
  - metabolism and vitamin D processing changes in response to changes in diet after the rise of agriculture

All these traits go beyond just increasing the odds of survival, they improve the life of the individual directly. I.e. they confer fitness. Individuals carrying those traits will, on average, in that ecosystem they are inhabiting, be more healthy than those who don't.

▲ Symmetry 3 hours ago | parent | prev | next [-]

Not a tautology but a definition.

https://en.wikipedia.org/wiki/Fitness_(biology)

▲

bcjdjsndon 2 hours ago | parent [-]

But other than it surviving, there's no way to define fitness.

	▲	Symmetry 2 hours ago \| parent \| next [-]
		It's more reproducing than surviving. If the population of some species increases and the number of copies of some allele remains constant we could consider than gene less fit than the other alleles, in the population genetics sense. So it's frequency rather than survival that geneticists look at. But that proves that there are indeed other ways that they could have defined fitness if they wanted to.
	▲	johngossman 2 hours ago \| parent \| prev [-]
		That is correct. Biology uses the term fit slightly different than the general public

▲ fluidcruft 2 hours ago | parent | prev | next [-]

The flip side is everything is being degraded by random mutation.

It's like holding a large ball in place on a hill that sees frequent tremors. If the ball is still halfway up the hill it's being held in place, if it's being held in place it's still halfway up the hill. It might be considered a tautology if you're only working with symbols and ignore all the mechanistics.

	▲	astrobe_ 5 minutes ago \| parent [-]
		> The flip side is everything is being degraded by random mutation "degraded"? Aren't random mutations precisely one of the core mechanism of adaptation?

▲ nine_k 2 hours ago | parent | prev [-]

Whatever does not survive stops registering in later times; most of the time, what helps survival is retained, and what helps survival is what increases fitness.

	▲	taeric 2 hours ago \| parent [-]
		As stated, this feels wrong. Specifically, it does not account for traits being appropriate for environment. I like to say it as what was needed for one stage could be the problem for the next stage. That is, traits that stop registering may no longer be something that helps survival. But that does not mean they were not necessary for survival at an earlier point.