General Question

Zyx's avatar

How is evolution measured?

Asked by Zyx (4011 points ) October 5th, 2010

I’m looking for something that expresses evolution directly instead of adressing the time and extent of the evolution seperately. Something like “Losing their tails cost humans 4 Darwins”??? With the length of a single Darwin depending on birth rates and total fertility rates. Of course the chance of the mutation would have to be in there as well but I’m mostly wondering if something like this exists already?

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24 Answers

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RocketGuy's avatar

I have never seen any evolutionary time scale, aside from years. There is a fairly constant rate of genetic change, but I don’t think it has its own name.

Qingu's avatar

We can directly compare organisms’ DNA, and can often date the mutations that separate them, and we can get a good sense of how a species’ DNA varies across its population.

But, you probably won’t find a simple one-to-one measurement system here because genetics is extremely complicated.

crisw's avatar

Evolution is measured by genome change. There are many molecular clocks that are used. This may be the kind of thing you are looking for.

gorillapaws's avatar

The rate of evolution is very far from constant. A large and stable population might not make any changes for a long time, then suddenly some external selective pressure may arise and the species may evolve rapidly. As I understand it, the smaller the population, the more rapidly it is capable of evolving.

Zyx's avatar

@crisw I’ll take a better look at that later but it’s certainly part of what I mean, and fascinating. My point was the calculations of evolution should not be all that complicated, but immensely useful.

the100thmonkey's avatar

Why shouldn’t they be complicated?

lillycoyote's avatar

I agree with @the100thmonkey Why shouldn’t the “calculations” be complex?

Though I really, really like the idea of the “darwin.” LOL. After all, we have the amp, the kelvin, the watt, the hertz, the joule, the volt, etc. why shouldn’t there be a “darwin”? The question is just what would the “darwin” be a specific quantity of, exactly?

Zyx's avatar

@the100thmonkey

Well, evolution is like a delicious cake made from causality and occam’s razor. All it says is that amongst selfreplicating entities, the survivor gets to have more replicas. So though we miss a lot of data (mutation ratios, environmental factors), what’s really relevant to evolution is the percentage of people to have how many children when they’re how old. We still need some mutation ratios, but those can be extrapolated from the fossils for now.

Maybe we just have different definitions of complicated.

@lillycoyote The Darwin is a quantity of evolutionary progress. And as I’m writing this I realise it’s a beautiful tool for eugenics.

crisw's avatar

@Zyx

“The Darwin is a quantity of evolutionary progress.”

But how would you define that, exactly?

Don’t fall into the trap of thinking that evolution being a process designed to produce “higher” or “more complex” organisms.

Zyx's avatar

@crisw That’s exactly what it is, you’re just limited to a planetary scale over a couple billion years. That’s really really tiny on a universal scale.

Qingu's avatar

@Zyx, Newton’s laws are very simple, but the calculation for the orbits of three bodies is ridiculously complicated (iirc modern supercomputers can just barely do it).

Zyx's avatar

@Qingu And my point was you don’t need to work out the chemistry in order to observe evolution. You do if you want to be exactly right but I’ll consider that discovery chemical. Leaving the calculations of evolution pretty damn simple.

crisw's avatar

@Zyx

“That’s exactly what it is”

What is exactly what it is? I am not sure what you are referring to.

Qingu's avatar

@Zyx, you don’t need to work out the three-body problem to observe the orbits of the moon and earth around the sun.

I see what you’re saying about abstracting the chemical interactions that underlie evolution (Newton’s laws also abstract the quantum mechanical stuff that underlies force, mass, and momentum). But even so, applying the simple laws of evolution is extremely complicated.

I guess what you’re asking for can be thought of as analogous to “units,” but look at any physical theory and units aren’t defined in its simple laws. Like, what the hell is a kilogram? It’s an arbitrary, manmade definition, just like our definition of “species.”

Zyx's avatar

@crisw That’s exactly what evolution is, a process that brings forth increasingly complex and capable life.

@Qingu I agree with most of what you’re saying but I’m actually looking for something as simple as a kilogram, we can figure out the equivalent of a unit later. But I guess if something existed yet someone would have spoke up. I best get on this, to the moon bitch!

Qingu's avatar

@Zyx, I think a “species” is probably a good analog to an SI unit for physics. Species differ from each other in a way defined as “they don’t typically breed.”

Though, like a kilogram, there’s nothing special about this designation on a deeper/more fundamental level (the genes).

Qingu's avatar

I actually agree that evolution can be thought of as progress. I can understand @crisw‘s trepidation with labeling it as such, especially because conservatives tend to strawman evolution as “things are always getting better.”

But at the same time, evolution does seem to have a direction, which corresponds to organisms with greater intelligence and complexity over time. I’m comfortable calling that a kind of progress. There’s a book called Nonzero that fleshes out this idea.

lillycoyote's avatar

@Zyx I was just joking about the “darwin.”

And eugenics doesn’t need or deserve or have the capacity to provide a “beautiful tool.” We have yet to confront and acknowledge and rid ourselves completely of its more than plentiful ugly tools.

crisw's avatar

@Zyx

“That’s exactly what evolution is, a process that brings forth increasingly complex and capable life.”

Define “capable.”

In the evolutionary sense, what evolution brings forth is organisms that are successful at passing on their genes- that is all that “capable” could meaningfully define.. But this doesn’t mean that the organisms are then more complex. The majority of multicellular species on Earth are parasitic. And being a parasite often involves a loss of what we would usually term complexity- entire organ systems, for example.

Dr_Lawrence's avatar

You are looking for a simple unit that encompasses the multiple dimensions in evolution and speciation. Biological science is more complex that you may like, but if you want to understand, you will have to stufy and learn enough to begin to understand what factors are involved.

Sorry, there are no simple answers that one can learn while standing on one foot.

mattbrowne's avatar

- rate of mutation i.e. number of changed base pairs in a given time frame
– selection pressure in conjunction with reproduction cycles i.e. number of surviving bacteria during antibiotic treatment

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