Myths and misconceptions about evolution - Alex Gendler
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0:14 - 0:18Myths and misconceptions about evolution.
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0:18 - 0:21Let's talk about evolution.
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0:21 - 0:21You've probably heard
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0:21 - 0:24that some people consider
it controversial, -
0:24 - 0:26even though most scientists don't.
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0:26 - 0:28But even if you aren't one of those people
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0:28 - 0:31and you think you have a pretty
good understanding of evolution, -
0:31 - 0:33chances are you still believe
some things about it -
0:33 - 0:35that aren't entirely right,
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0:35 - 0:37things like,
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0:37 - 0:41"Evolution is organisms
adapting to their environment." -
0:41 - 0:42This was an earlier,
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0:42 - 0:44now discredited,
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0:44 - 0:46theory of evolution.
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0:46 - 0:49Almost 60 years before Darwin
published his book, -
0:49 - 0:51Jean-Baptiste Lamarck proposed
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0:51 - 0:52that creatures evolve by developing
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0:52 - 0:55certain traits over their lifetimes
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0:55 - 0:58and then passing those
on to their offspring. -
0:58 - 1:00For example, he thought
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1:00 - 1:02that because giraffes spent their lives
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1:02 - 1:05stretching to reach leaves
on higher branches, -
1:05 - 1:08their children would be
born with longer necks. -
1:08 - 1:12But we know now that's not
how genetic inheritance works. -
1:12 - 1:16In fact, individual organisms
don't evolve at all. -
1:16 - 1:19Instead, random genetic mutations cause
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1:19 - 1:22some giraffes to be
born with longer necks, -
1:22 - 1:24and that gives them
a better chance to survive -
1:24 - 1:26than the ones who weren't so lucky,
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1:26 - 1:28which brings us to
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1:28 - 1:31"survival of the fittest".
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1:31 - 1:34This makes it sound
like evolution always favors -
1:34 - 1:35the biggest,
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1:35 - 1:36strongest,
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1:36 - 1:38or fastest creatures,
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1:38 - 1:40which is not really the case.
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1:40 - 1:43For one thing, evolutionary
fitness is just a matter -
1:43 - 1:47of how well-suited
they are to their current environment. -
1:47 - 1:49If all the tall trees suddenly died out
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1:49 - 1:51and only short grass was left,
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1:51 - 1:52all those long-necked giraffes
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1:52 - 1:55would be at a disadvantage.
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1:55 - 1:59Secondly, survival is not
how evolution occurs, -
1:59 - 2:01reproduction is.
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2:01 - 2:02And the world if full of creatures
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2:02 - 2:04like the male anglerfish,
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2:04 - 2:07which is so small and ill-suited
for survival at birth -
2:07 - 2:11that it has to quickly find
a mate before it dies. -
2:11 - 2:12But at least we can say
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2:12 - 2:14that if an organism dies
without reproducing, -
2:14 - 2:17it's evolutionarily useless, right?
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2:17 - 2:18Wrong!
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2:18 - 2:20Remember, natural selection happens
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2:20 - 2:22not at the organism level,
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2:22 - 2:23but at the genetic level,
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2:23 - 2:26and the same gene
that exists in one organism -
2:26 - 2:28will also exist in its relatives.
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2:28 - 2:31So, a gene that makes an animal
altruistically sacrifice itself -
2:31 - 2:34to help the survival
and future reproduction -
2:34 - 2:36of its siblings or cousins,
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2:36 - 2:37can become more widespread
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2:37 - 2:41than one that is solely concerned
with self-preservation. -
2:41 - 2:43Anything that lets more copies of the gene
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2:43 - 2:45pass on to the next generation
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2:45 - 2:47will serve its purpose,
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2:47 - 2:49except
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2:49 - 2:52evolutionary purpose.
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2:52 - 2:55One of the most difficult things
to keep in mind about evolution -
2:55 - 2:57is that when we say things like,
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2:57 - 3:01"Genes want to make more
copies of themselves," -
3:01 - 3:01or even,
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3:01 - 3:03"natural selection,"
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3:03 - 3:06we're actually using metaphors.
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3:06 - 3:08A gene doesn't want anything,
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3:08 - 3:10and there's no outside mechanism
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3:10 - 3:14that selects which genes
are best to preserve. -
3:14 - 3:17All that happens is that random
genetic mutations -
3:17 - 3:19cause the organisms carrying them
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3:19 - 3:21to behave or develop in different ways.
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3:21 - 3:23Some of those ways result in more copies
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3:23 - 3:25of the mutated gene being passed on,
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3:25 - 3:26and so forth.
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3:26 - 3:27Nor is there any predetermined plan
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3:27 - 3:31progressing towards an ideal form.
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3:31 - 3:33It's not ideal for the human
eye to have a blind spot -
3:33 - 3:35where the optic nerve exits the retina,
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3:35 - 3:37but that's how it developed,
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3:38 - 3:40starting from a simple photoreceptor cell.
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3:40 - 3:42In retrospect, it would have been
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3:42 - 3:44much more advantageous for humans to crave
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3:44 - 3:45nutrients and vitamins
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3:45 - 3:47rather than just calories.
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3:47 - 3:48But over the millenia,
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3:48 - 3:50during which our ancestors evolved,
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3:50 - 3:51calories were scarce,
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3:51 - 3:53and there was nothing to anticipate
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3:53 - 3:56that this would later change so quickly.
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3:56 - 3:59So, evolution proceeds blindly,
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3:59 - 4:00step
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4:00 - 4:02by step
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4:02 - 4:03by step,
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4:03 - 4:07creating all of the diversity
we see in the natural world.
- Title:
- Myths and misconceptions about evolution - Alex Gendler
- Speaker:
- Alex Gendler
- Description:
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View full lesson: http://ed.ted.com/lessons/myths-and-misconceptions-about-evolution-alex-gendler
How does evolution really work? Actually, not how some of our common evolutionary metaphors would have us believe. For instance, it's species, not individual organisms, that adapt to produce evolution, and genes don't "want" to be passed on -- a gene can't want anything at all! Alex Gendler sets the record straight on the finer points of evolution.
Lesson by Alex Gendler, animation by Giant Animation Studios.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:23
Krystian Aparta edited English subtitles for Myths and misconceptions about evolution | ||
Jessica Ruby approved English subtitles for Myths and misconceptions about evolution | ||
Jessica Ruby accepted English subtitles for Myths and misconceptions about evolution | ||
Jessica Ruby edited English subtitles for Myths and misconceptions about evolution | ||
Jessica Ruby edited English subtitles for Myths and misconceptions about evolution | ||
Andrea McDonough edited English subtitles for Myths and misconceptions about evolution |