Biological fitness - What Is It?

CoIin: I'd be interested to hear the thoughts of other members on the issue of biological "fitness". There is another thread running in the Science Forum ( "The So-Called Science of Evolution..." ) at the moment in which this topic has been broached, but since that particular thread resembles a war zone, and since its existence depends on the caprice of its creator, I thought it would be better to start a new thread.

Let's begin by introducing what we'll call "Corvin's Challenge". This is how he presented it in the abovementioned thread:-


"Here's a good point for any of those who like to believe in "divine intervention" in the struggle of life.---
We like to refer to "the survival of the fittest"... if anybody can show me an example of a "less than fit" species winning over against a "more fit" species, maybe because God sent lightning bolts down and changed the outcome, then we would be glad to see this evidence... and we certainly would have a few things to consider with our silly notions of "natural selection". "


Corvin has actually raised a fascinating question, and a very subtle question, which is by no means as trivial as it might appear on the surface. Corvin presented this challenged once before in another thread, and I'm no longer convinced that the answer I gave on that occasion was correct.

First, let's look at the basic problem, which is "Can Corvin's Challenge be met?". The question is, are we dealing with what philosophers call an "analytic" claim, or are we dealing with a "synthetic" claim, that is to say, is this a matter of logic or is it a matter of real world facts?

For example, if I challenge you to show me a married bachelor, you're not going to succeed. You don't even need to leave your armchair. This is a LOGICAL impossibility.

CoIin: On the other hand, if I challenge you to show me a bird that doesn't lay eggs, this is an EMPIRICAL challenge (unless, of course, I include "egg-laying" as part of the definition of "bird" in which case any non-egg-laying creature you present to me is by definition "not a bird" ) . There is nothing logically impossible about a bird not laying eggs. We'd need to get out there and look.

So which kind is Corvin's Challenge - analytic or synthetic? - logical or empirical? If fitness is defined as "survival and reproduction" then Corvin's challenge is of the former kind and is clearly insurmountable, as impossible as discovering a square circle.

Or does Corvin's Challenge belong to the latter kind? Is there anything over and above survival and multiplication that allows us to tell which organisms are more fit?

Perhaps an example will help to make this all more clear. Let's say I present evidence of two species which lived during the same period, in the same environment - call them Shorts and Longs. The Shorts went extinct after a relatively short time while the Longs continued to thrive long thereafter.

I present evidence to Corvin that the Longs were less fit than the Shorts. Perhaps I point out their relatively poor eyesight, or weak forelimbs, or other physical features.

So it's crunch time. Have I met the challenge?

Now, if Corvin says "No, the Shorts were clearly less fit."

And I ask "Why?"

And Corvin says "Because they didn't survive. They went extinct sooner. They lost in the struggle to the Longs."

If this is the case, then we're all wasting our time. Meeting Corvin's Challenge is a logical impossibility. We might as well search our family trees for ancestors who produced no offspring.

Have I made the point clear? I hope you're all with me.

So my question to the others is, "How do we decide which organisms are fitter?" Are the fittest purely the survivors? Or is there any physical way to distinguish them? What does biology say about this? Did Darwin discuss this?

CrisC: This is a very good question. If you somehow presented evidence showing that these "Longs" really were less adapted to the environment than these "Shorts", but they survived anyways, then Colin couldn't just state "No, the Shorts were clearly less fit" and nothing else. That's just stating the contradictory idea without anything to back it up.

The whole "survival of the fittest" thing is pretty misleading...I think it's mostly used by people that don't understand evolution very well, or perhaps it was originally used in order to easily convey a complicated subject into very easy to understand terms.

Berkeley University instructs undergraduate teachers to avoid using the phrase "survival of the fittest", since it oversimplifies a complicated subject and leaves people with the wrong impression. It is not a constant life or death struggle against competitors, there are many more factors.

Biological fitness really comes down to what is "fit enough" to survive, not the fittest. It may seem like a tiny thing, but it makes a difference in meaning.

Now, I realize it may sound redundant... Survival of the ones most likely to survive. This is why I don't personally care for the phrase, it seems to state the painfully obvious and then go on to oversimplify it all.

It seems to me that Colin is saying if you can show an animal very poorly adapted for it's ecological niche winning over an animal better adapted, it would cause serious problems. If this really happened in nature, it should possible to show it.

Of course, we know it is the animal most likely to survive that will survive. This is why conservationists freak out when a non-native, invasive species is artificially introduced to a natural environment...If it's better at the niche than the other occupier of it is, it will drive it to extinction (or it could evolve for a new niche) given enough time.

CoIin: Yes, this is the whole problem. How could one possibly demonstrate that the Longs or the Shorts are "less adapted to the environment" other than invoking survival and multiplication statistics?

Look! There's a bird species that doesn't lay eggs!

How can you tell?

Ans : We've observed it giving birth to live young.




Look! There's a less fit species (A) outdoing a more fit species (B) !

How can you tell A is less fit than B?

Ans :


And Psst. I think you've said "Colin" (twice) in your post above when you mean "Corvin"

AussieOi: Well once you've actually spat out your question here Col, maybe I have an analogy to nudge a mild suggestion towards an answer.

Think of yourself not as yourself but a whole collective bunch of cells and bacterium working as one basic unit. They get together and survive better in a more diverse and organised way than alone. It might not be survival of the fittest as much as survival of the collectivists. But then collective can be fit.

CoIin: The first time Corvin presented this challenge, I rejected it as unreasonable on the grounds that it was a logical impossibility.

These days (and I did a little googling), I'm inclining to the position that it's still an unreasonable challenge - a challenge that can never be met - but on practical rather than logical grounds.

For example, if I were to claim that all human actions are determined purely by physical laws, a religious free will advocate might challenge me by saying "Ok, tell me everything that Smith will do tomorrow."

Clearly there is no way I'll be able to prevail. Not for logical reasons, and not because it's impossible in principle, but purely down to epistemic reasons - humans just don't know enough to meet a challenge like that.

MercuryDragon: Simple answer: I am biological fitness.

CoIin:

CrisC: Assuming a less adapted species really could win out over a more adapted species, it would still be extremely difficult to show. You'd probably have to be able to be able to observe and record it happening with nobody able to come up with an explanation as to why the apparently more "fit" species is dying off.

CoIin: I can never help making Wordy analogies...

So, here's the scenario. Draigo has just beaten me 10 - 0. I respond rather unsportingly, "Yeah yeah yeah. Pfft and meh and harumph. He won on points but I'm a better player."

And we've all heard disgruntled football teams make similar claims.

Does this make any sense? Well, if the "good-bad player" distinction is isomorphic with the "win-lose" distinction then it makes no sense at all. The better player JUST IS the player who wins in competition.

Likewise with fitness. It seems to me, for the term to be meaningful, and for Corvin's Challenge to stand any chance of being met, we would need to show that the "fit-unfit" distinction is not isomorphic with the "survive-perish" distinction.

In other words, we would need some criteria by which fitness is to be judged which do NOT correspond to survival rates.

Can this be done?

duncan124:
Lets have a think about this. Old Colins posts are less then cheerful 'bon homenies', infact there is sometimes a sinister craving for attention.

eg "...claim, that is to say, is this a matter of logic or is it a matter of real world facts?" Colin says while knowing it seems the answer to his question.

Geoff: Colin - you should know better.

Natural selection doesn't favour competition between different species, but differing members of the same species.

CoIin: Do we know this, Geoff?

I'm no expert on this, but I thought the unit of natural selection was a matter of some dispute, whether it be individual organisms, groups of individuals, or even the gene (as in the Selfish Gene).

Geoff: Then you need to re-read 'On the origin of the species by natural selection'.

While the actions of one species may affect another's ability to breed, that is an "environmental change". Natural selection specifically details the changes in predominant characteristics caused by competition between different members of the same species.

When Spencer coined the phrase, "Survival of the fittest" he was referring most specifically selection of those most suited to live long enough to breed.

Yes, Dawkins has refined evolutionary theory to the point of the survival of genetic traits (the Selfish Gene), such behavioural adaptations would still only affect the competition between competing individuals only within the species.

This might result in the extinction of another species, but from an objective standpoint, this is an environmental issue, not an evolutionary one.

duncan124:
Common sense will tell that it is all of those things and any more that come along. Evolution is a real world fact or fiction.

'Natural Selection' did mean the species but clearly most living things depend on others and the environment to boot. So it is often a very fluid situation.

CoIin: @ Geoff



Hmm, if that's the case, this would appear to render Corvin's Challenge, and my thread, null and void. Correct?

duncan124:
Correct.

Geoff: Not necessarily, you just reword it slightly.

Instead of two different species, it would be two different groups within the same species.

CoIin: Cool. Ok, we're back in business, guys.

CoIin: So what do you say, Geoff? Is there anything to "fitness" over and above survival and multiplication rates?

Geoff: However, if the environment did include such a powerful intelligence that could arbitrarily wipe out large population groups, then staying on such a monster's good side would clearly make those survivors more fit.

Aura: I think it is 'fit' that's throwing you off a bit. Fit here doesn't mean that they are stronger, just that they have a better chance of getting what they need. If the longs could reach the food source because of their high, and the shorts didn't, well then the longs are fitter than the shorts.
And if they are not predatory, who cares about eyesight or how weak the limbs are, those fruits are high up in a tree, all that is needed is height.

Survival of the fittest only relates to natural selection in the sense that dead creatures can't mate. Selection is about making a attractive appearance to the opposite sex and it is very true that there is no logic in this. Look at the peacock. That tail is a big sign for predators "tasty snack here". But the lady peacocks like it, so it survived. Now you can bring survival of the fittest in, saying , yeah, but the birds who had eye like patterns on it, confused the predator and lived long enough to mate, thus we got all peacocks with the now familiar feathers....and so on. Does that tail make em fitter? yes, it does, even though it really has not all that much advantage for survival.

Geoff: But, since there is zero credible evidence of such a being, I'll stick with using my brain to think and not bash against the lobotomising wall of worship.

Geoff: Yes, "fit" in this case purely refers to "Most able to survive and pass on one's genes".

CoIin: Um, shouldn't that be "No, "fit" in this case purely refers to "Most able to survive and pass on one's genes"?



Are you saying there is nothing to fitness over and above survival and multiplication rates?

Aura: Only humans ask if you even lift, bro....