Myths and misconceptions about evolution - Alex Gendler

Myths and misconceptions about evolution.

Let's talk about evolution.

You've probably heard

that some people consider it controversial,

even though most scientists don't.

But even if you aren't one of those people

and you think you have a pretty good understanding of evolution,

chances are you still believe some things about it

that aren't entirely right,

things like,

"Evolution is organisms adapting to their environment."

This was an earlier,

now discredited,

theory of evolution.

Almost 60 years before Darwin published his book,

Jean-Baptiste Lamarck proposed

that creatures evolve by developing

certain traits over their lifetimes

and then passing those on to their offspring.

For example, he thought

that because giraffes spent their lives

stretching to reach leaves on higher branches,

their children would be born with longer necks.

But we know now that's not how genetic inheritance works.

In fact, individual organisms don't evolve at all.

Instead, random genetic mutations cause

some giraffes to be born with longer necks,

and that gives them a better chance to survive

than the ones who weren't so lucky,

which brings us to

"survival of the fittest".

This makes it sound like evolution always favors

the biggest,

strongest,

or fastest creatures,

which is not really the case.

For one thing, evolutionary fitness is just a matter

of how well-suited they are to their current environment.

If all the tall trees suddenly died out

and only short grass was left,

all those long-necked giraffes

would be at a disadvantage.

Secondly, survival is not how evolution occurs,

reproduction is.

And the world if full of creatures

like the male anglerfish,

which is so small and ill-suited for survival at birth

that it has to quickly find a mate before it dies.

But at least we can say

that if an organism dies without reproducing,

it's evolutionarily useless, right?

Wrong!

Remember, natural selection happens

not at the organism level,

but at the genetic level,

and the same gene that exists in one organism

will also exist in its relatives.

So, a gene that makes an animal altruistically sacrifice itself

to help the survival and future reproduction

of its siblings or cousins,

can become more widespread

than one that is solely concerned with self-preservation.

Anything that lets more copies of the gene

pass on to the next generation

will serve its purpose,

except

evolutionary purpose.

One of the most difficult things to keep in mind about evolution

is that when we say things like,

"Genes want to make more copies of themselves,"

or even,

"natural selection,"

we're actually using metaphors.

A gene doesn't want anything,

and there's no outside mechanism

that selects which genes are best to preserve.

All that happens is that random genetic mutations

cause the organisms carrying them

to behave or develop in different ways.

Some of those ways result in more copies

of the mutated gene being passed on,

and so forth.

Nor is there any predetermined plan

progressing towards an ideal form.

It's not ideal for the human eye to have a blind spot

where the optic nerve exits the retina,

but that's how it developed,

starting from a simple photoreceptor cell.

In retrospect, it would have been

much more advantageous for humans to crave

nutrients and vitamins

rather than just calories.

But over the millenia,

during which our ancestors evolved,

calories were scarce,

and there was nothing to anticipate

that this would later change so quickly.

So, evolution proceeds blindly,

step

by step

by step,

creating all of the diversity we see in the natural world.