Natural Selection – Crash Course Biology #14

Natural Selection – Crash Course Biology #14


Hi, I’m Hank. And I’m a human,
but let’s pretend for a moment that I’m a moth. And not just
any moth, a peppered moth. Now let’s pretend that I’m living
in London in the early 1800s, right as the industrial revolution
is starting. Life is swell. My light-colored body lets me
blend in with the light-colored lichens and tree bark, which means
birds have a hard time seeing me, which means that I get to live. But it’s starting to get noticeably darker
around here with all these coal-powered factories spewing
soot into the air, and suddenly all the trees have gone from
looking like this to looking like this. So thanks to the soot-covered
everything, I’ve got problems. But you know who doesn’t have
problems? My brother. He looks like this Yeah,
he has a different form of the gene that
affects pigmentation. Moths like him represent about
2 percent of all the peppered moths at the start of the
industrial revolution. But by 1895 it’ll be 95 percent! Why? Well, you’re probably already
guessing, as the environment gets dirtier, darker moths will be
eaten less often, and therefore have more opportunities
to make baby moths. The white ones will get eaten
more, so over time, the black-colored trait
will become more common. As for me? [Eaten.] This, my friends, is a
wonderful example of natural selection. The process by
which certain inherited traits make it easier for some
individuals to thrive and multiply, changing the genetic makeup
of populations over time. For this revelation, which remains
one of the most important revelations in biology, we have to
thank Charles Darwin, who first identified this process in his
revolutionary 1859 book, On the Origin of Species
by Natural Selection. Now lots of factors play a role
in how species change over time including mutation, migration and
random changes in how frequently some alleles show up, a
process known as genetic drift. But natural selection is the most
powerful and most important cause of evolutionary change, which is
why today we’re going to talk about the principles behind it,
and the different ways in which it works. Darwin came to understand the
process of selection because he spent his adult life, even most of
his childhood, obsessed with observing nature. He studied barnacles, earthworms,
birds, rocks, tortoises, fossils, fish, insects and to some extent,
even his own family. I’ll get back to that in a bit. But it was during Darwin’s famous
voyage on the H.M.S. Beagle in the 1830s, a surveying
expedition around the world, that he began to formulate
this theory. Darwin was able to study all kinds of organisms,
and he kept amazing journals. Looking back on his notes,
he hit upon a couple of particularly important factors
in species’ survival. One of them was the many examples
of adaptations he noticed on his journey. The ways in which
organisms seemed to be nearly ideally shaped to enhance their
survival and reproduction in specific environments. Maybe the most famous example of
these were the variations of beaks Darwin observed among the finches
in the remote Galapagos Islands off the coast of South America.
He observed more than a dozen closely-related finch species,
all of which were quite similar to mainland finch species,
but each island species had different shaped and sized beaks
that were adapted to the food available specifically
on each island. If there were hard seeds,
the beaks were thick. If there were insects,
the beaks were skinny and pointed. If there were cactus fruit,
the beaks were sharp to puncture the fruit’s skin. These superior inherited traits
led Darwin to another idea, the finches’ increased fitness for
their environment, that is, their relative ability to survive
and create offspring. Explaining the effects of
adaptation and relative fitness would become central to Darwin’s
idea of natural selection. And today we often define natural
selection, and describe how it drives evolutionary change,
by four basic principles, based on Darwin’s observations. The first principle is that
different members a population have all kinds of
individual variations. These characteristics,
whether their body size, hair color, blood type,
facial markings, metabolisms or reflexes, are called phenotypes. The second is that many variations
are heritable and can be passed on to offspring. If a trait
happens to be favorable, it does future generations no
good if it can’t be passed on. Third: this one tends to get
glossed over a lot, even though it’s probably the most interesting,
is Darwin’s observation that populations can often have way
more offspring than resources, like food and water, can support. This leads to what Darwin called
“the struggle for existence.” He was inspired here by the work
of economist Thomas Malthus, who wrote that when human
populations get too big, we get things like plague
and famine and wars, and then only some of us survive
and continue to reproduce. If you missed the SciShow Infusion
that we did on human overpopulation today and Malthus’s predictions,
you should check it out now. This finally leads to the last
principle of natural selection, which is that, given all of this
competition for resources, heritable traits that affect
individuals’ fitness can lead to variations in their survival
and reproductive rates. This is just another way of saying
that those with favorable traits are more likely to come out on top
and will be more successful with their baby-making. So to wrap all these principles
together, in order for natural selection to take place,
a population has to have variations, some of which are
heritable, and when a variation makes an organism more competitive,
that variation will tend to be selected. Like with the peppered moth.
It survived because there was variation within the species,
the dark coloration, which was heritable,
and in turn allowed every moth that inherited that trait to better survive the
hungry birds of London. But notice how this works.
A single variation in a single organism is only the very
beginning of the process. The key is that
individuals don’t evolve. Instead, natural selection
produces evolutionary change because it changes the genetic
composition of entire populations, and that occurs through
interactions between individuals and their environment. Let’s get back to Darwin
for a minute. In 1870, Darwin wrote to his
neighbor and parliamentarian John Lubbock requesting that a
question be added to England’s census regarding the frequency
of cousins marrying and the health of their offspring. His request was denied,
but the question was something that weighed heavily on
Darwin’s mind, because he was married to
Emma Wedgwood, who happened to be his first cousin. Her grandfather was
Josiah Wedgwood, founder for the company that
remains famous for its pottery and china. Oh, and he was also
Darwin’s grandfather. In fact, much of Darwin’s family
tree was…complicated. His marriage to Emma was far from
the first Wedgewood-Darwin pairing. Darwin’s maternal grandparents and
mother were also Wedgwoods, and there were several other
marriages between cousins in the family, though not always
between those two families. So Darwin, and to a greater extent
his children, carried more genetic material of Wedgwood origin than
Darwininan. And this caused some problems, the likes of which
Darwin was all too aware of, thanks to his own scientific research. Darwin of course spent time
studying the effects of crossbreeding and inbreeding
in plants and animals, noting that consanguineous pairs
often resulted in weaker and sickly descendants. And the
same was true of his family. Emma and Charles had 10 children,
three of whom died in childhood from infectious disease,
which is more likely to be contracted by those with
high levels of inbreeding. And while none of Darwin’s seven
other children had any deformities, he noted that they were
“not very robust” and three of them were unable to
have children of their own, likely another effect of inbreeding. Now, so far we’ve been talking
about natural selection in terms of physical characteristics,
like beak shape or coloration. But it’s important to understand
that it’s not just organism’s physical form, or its phenotype,
that’s changing but its essential genetic form,
or genotype. The heritable variations we’ve
been talking about are a function of the alleles that organisms are
carrying around. And as organisms become more successful,
evolutionarily speaking, by surviving in larger numbers for
longer and having more kids, that means that the alleles that
mark their variation become more frequent. But these changes can come about
in different ways. To understand how, let’s walk
through the different modes of selection. The mode we’ve been talking about
for much of this episode is an example of directional selection,
which is when a favored trait is at one extreme end of the range of
traits, like from short to tall, or white to black, or blind to
having super-night-goggle vision. Over time this leads to distinct
changes in the frequency of that expressed trait in a population,
when a single phenotype is favored. So our peppered moth is an example
of a population’s trait distribution shifting toward one
extreme, almost all whitish moths, to the other extreme,
almost all blackish. Another awesome example is
giraffe necks. They’ve gotten really long over time because
there was selection pressure against short necks, which
couldn’t reach all of those delicious leaves. But there’s also stabilizing
selection, which selects against extreme phenotypes and instead
favors the majority that are well adapted to an environment.
An example that’s often used is a human’s birth weight: Very small
babies have a harder time defending themselves from infections and
staying warm, but very large babies are too large to deliver
naturally. Because of this, the survival rate for babies has
historically been higher for those in the middle weight range,
which helped stabilize average birth weight.
At least, until Cesarian sections became as common as bad tattoos. So what happens when the
environment favors extreme traits at both ends of the spectrum,
while selecting against the common traits?
That’s disruptive selection. Now examples of this are rare,
but scientists think they found an instance of it in 2008, in a
lake full of tiny crustaceans called Daphnia.
The population was hit with an epidemic of yeast parasite,
and after about a half-dozen generations, a variance had
emerged in how the Daphnia responded to the parasite.
Some became less susceptible to the yeast, but were smaller and
had fewer offspring. The others actually became more susceptible
to the parasite, but were bigger and able to reproduce more,
at least while they were still alive.
So there were two traits that were being selected for, both in
extremes and both to the exclusion of each other: susceptibility
and fecundity. If you got one,
you didn’t get the other. An interesting example,
of selection being driven by a parasite. Now while these are the main ways
that selective pressures can affect populations, those
pressures can also come from factors other than environmental
ones like food supply or predators or parasites.
There’s also sexual selection, another concept introduced by Darwin and described in The Origin
of Species as depending “not on a struggle for existence,
but a struggle between individuals of the same sex, generally the
males, for the possession of the other sex.” Basically, for individuals to
maximize their fitness, they not only need to survive but
they also need to reproduce more, and they can do that one
or two ways: One, they can make themselves
attractive to the opposite sex. Or two, they can go for the upper
hand by intimidating, deterring or defeating the same-sex rivals. The first of these strategies is
how we ended up with this: I mean, the peacock tail isn’t
exactly camouflage. But the more impressive the tail, the better
chances a male will find a mate and pass its genes
to the next generation. Sad-looking peacock tails will
diminish over generations, making it a good example
of directional sexual selection. The other strategy involves
fighting, or at least looking like=you want to fight, for the
privilege of mating, which tends to select for
bigger or stronger or meaner-looking mates. And finally, thanks to us humans
there are also un-natural forms of selection, and we call
that artificial selection. People have been artificially
selecting plants and animals for thousands of years, and Darwin
spent a lot of time in Origin of Species talking about the breeding
of pigeons and cattle and plants to demonstrate the
principles of selection. We encourage the selection of some
traits and discourage others. It’s how we got grains that
produce all those nutrients. Which is how we managed to turn
the gray wolf into domesticated dogs that can look like this or like that, two of my favorite
examples of artificial selection. Now these are different
breeds of dogs- Oh, where you goin’?
No. No. But they’re both still dogs.
They’re the same species. Technically, a corgi and a
greyhound could get together and have a baby dog, though it would
be a weird looking dog. But, what happens when selection
makes populations so different that they can’t even be the same
species any more? Well, that’s what we’re going to talk about next episode on Crash Course Biology: How one species can turn into another species. In the meantime, feel free to
review what we’ve gone over today, ask us questions down in the comments below, or on Facebook or Twitter, We’ll see you next time.

100 comments

  1. It is CRIMINAL to us H.B.D. Kettlewell’s 19th century peppered moths to teach natural selection. 1) Kettlewell’s photos were staged. He PINNED the moths to the trees. 2) Peppered moths don’t rest on tree trunks and they DON’T rest with their wings outstretched. 3) They rest UNDER branches where coloration is nearly meaningless. 4) Bats also eat moths and they use echolocation to find prey, not sight. 4) Absolutely NO evolution of peppered moths took place either before or after the industrial revolution. All that changed (and later changed BACK) was the population distribution of light and dark coloration.

  2. Great GREAT video! Thank you so much for all of the information. I will be subscribing and watching all or your videos now. lol

  3. Natural selection does not produce new species, new genetic information or new organs. It can't cause anything to evolve.

  4. If I cut a big tree a little above its base I cannot join the two parts to recover the original tree. But, according evolution theory the "genes" tell the sequences needed to recover the original tree. Why is the cut tree is irrecoverable. Why is cut legs are not installable? If a leg of animal or human is cut totally then it is impossible to rejoin that cut parts? why? because their genes are not identifiable? thanks.

  5. Natural selection is a misleading term. The term selection implies that there are options to select from. There ate no options. The DNA suffers damage. It is a completely random event. On rare occasions the damage, completely by chance, offers a benefit to the creature. The fittest survive. That's it. Natural selection is a slave to a completely random process. Evolution is the greatest hoax in the history of the world.

  6. In all honesty humans need to have more natural selection I mean sexual preference is really just not enough lack of predators and since humans basically destroyed major diseases both killed off weaker humans and in all honesty humans maybe getting technologically stronger but in all honesty we are getting physically weaker every year and disagree with me if you want to call me a bad person for saying that but look around you it's happening as we speak.

  7. I understand how species is specialized has a special talent that are different from another this helps me a lot…..

  8. Darwin's theory was based on the mechanism of natural selection, which explains how populations can evolve in such a way that they become better suited to their environments within their environments overtime. Individuals have variatuons within their heritable traits.

  9. The explanation in the first minute almost exactly explains why humans evolved in africa to have dark brown/black skin……

    By:LAWRENCE ANTIPOLO

  10. I agree artificial selection can remove varations from a population thus causing less productivity in ecosystem trough the reduction og biodiversity. However when you stated that artificial selection allows animals and plants to be healtier,This is not althogether true. Trough same genes choosen can allow plants to be more desease resistant, most uses of artificial selection causes the animal to become genetically weaker.

    I think as long as humans don't go crazy with the artificial selection technology that we have however you're right, we dont need to be intefering with another animals need gene pool suit or needs.

    But overall this blog was very great it was very interisting and it help me a lot in my project thanks.

  11. This blog is very informative and useful especially to those people who are engaged in Agricultural Industry. Being able to give the advantages and disadvantages of the said topic is good. With that, readers can think wisely whether to engage to Artificial Selection or not. Also, clipping many pictures makes it appealing to read and easy to understand. In the end, I learned that Artificial Selection is important in terms that people will benefit from it through lots of agricultural produce but should be wise enough because it can affects the economy, environment and God’s plan of creation.

  12. This blog shows how people reacts to all living things in the earth. Thats why there is events that species change depends in the environment and the weather. This blog is helpful for those who are finding pets that is friendly, and we can know when the food is safe or it has poison or it has a bad effect on our body

  13. Hi! Thanks for this helpful blog. As a student it is very important for us to know more about the artificial selection. I also learned that we should give importance to the plants and animals because they are the ones who produce our food in our daily lives . And now because of your blog I knew the advantages ad disadvantages of artificial selection. Thank you for sharing your knowledge with us .

  14. Biodiversity is important to us without it there is no other life on Earth, including our own, This diversity of life is what provides a clean, water, oxygen, and all other things that end up being part of our diet as well as clothing and shelter so let us take care our environment and be responsible human being

  15. So in this blog i prove that this blog is all about birds and charles darwin is the scientist that support

  16. So i observe that is all about bidiversity of course theen is all about birds and charles darwin is the scientist that support this blog

  17. In this blog i prove that the bird can also involve in the biodiversity and charles darwin is supporter in this blog

  18. Thank you for the wonderful video😊 I've learned a lot from this video i knew that this kind of selection is the process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype constitution.

  19. One way to understand Evolution is to first understand “Artificial Selection”. Wolves and Dogs are descended from common ancestors (which looked more like modern wolfs than dogs). Over many generations, Humans selected the “favourable” traits (e.g., long shiny fur, or stocky legs etc) to produce the many different types / breeds of modern dogs that we have today. The keyword here is “over many generations”. There are modern dogs that, of course, are still very much wolve-like in appearance (e.g., Huskies, German Shepherd etc). Some dog breeds are much less wolf-like in appearance (Chihuahua, Shih Tzu etc) as they have been artificially selected for their small size and “cute” traits. So why is it known as artificial selection? This is because the Human (the dog breeders) are the ones determining which individual dogs they would prefer to produce offsprings, thereby continuing the genes they would like to retain. Prior to this, it is also important to understand the idea of Variation. This means that in a litter of puppies, not every puppy is physically identical (even though they may look identical to the untrained eyes). Some puppies have slightly longer legs, some shorter legs. Very small differences, but, yes, the differences are there. It is due to this physical variations that the breeders (humans) select which dogs possess the traits he wants, thus the term “Artificial Selection”. This Selection process is repeated over many generations and the result is the modern dog breeds we have today.

    Once we understood Artificial Selection, it will be easy to understand Natural Selection. In Natural Selection, the environment aka Mother Nature (instead of Human) is the factor deciding which traits survive through the generations. How? One example is Food Source. Many species of birds have developed the ability to swim to obtain their food (Adaptability). One pre-requisite of aquatic birds is having water-proof feathers. In this case, this is the “Favourable Trait”. One group of birds may live nearer to the seasides and Individual birds with better waterproof feathers is seen by Mother Nature as a “favourable trait”. And so individual birds with this trait has a much higher chance of survival and passing on this gene to the next generations. Birds with “less waterproof” feathers may probably not even live to adulthood as they had difficulties obtaining their food (in the sea), resulting in their genes being eliminated from this group of birds. Using an analogy, you may think of this process as a kind of filtration process, where only the finest particles is able to pass through the fine filter. This is Adaptation, and it has to be highlighted that Adaptation takes place over many, many, many generations. Physical Adaptations (e.g., change in body shapes) DO NOT take place in just one generation. In other words, an individual animal will not change its form physically to obtain that trait in its lifetime, unless it’s metamorphosis which is a totally different thing.

    We also observed this in rabbits living in deserts and rabbits living in cold countries. The long ears in rabbits act as effective heat radiators. This enables the rabbits to lose body heat efficiently, just as how humans lose heat efficiently by sweating. The rabbits living in deserts adapted (over many generations) to the environment by developing very long and erect ears for highly efficient lowering of their body temperature. But rabbits living in cold countries tends to have shorter ears (some even have lop ears). Shorter ears is the “favourable trait” here as it enables them to lose less body heat. All animals (and yes, that includes Humans) are still in the midst of Evolution. If Evolution is constantly ongoing, why can’t we see it happening? We need to understand that Evolution is a very, very slow on-going process. Evolution will never be “complete”, as change is the only constant. If Evolution is true, why are there no animals that are “neither here nor there” (i.e., in-between two species)? We need to remember humans are the ones who gave distinct names to different distinct species of animals in the first place. Let us look at the Seals / Walruses. Their ancestors are land animals, but their body shapes (flippers and hydrodynamic bodies) are hard evidence that they are in the midst of “transition” from land animals to aquatic animals, as their main source of food is in the sea. Of course, we cannot see an appreciable change in their appearances in our lifetime, as the change is happening far too slowly over many generations. So presently, we can only imagine the current physical appearances of Seals / Walruses as being “frozen-in-time”, as with the rest of the millions of species of animals currently living on this planet Earth. And do appreciate their beauty in their current physical form (and the diversity of the Tree of Life), as they will never be the same again one million years from now.

  20. Charles is stupid. Mutations never bring something new. No new information is ever added. Charles looked a bird and said they had a common ancestor. They probably did and it was a bird. But he said that the birds and bananas we’re related. He is stupid!!!!

  21. New organs or traits cannot emerge in living things through Natural selection. A species genetic data does not develop by means of it, and it cannot be used to account for the emergence of new species. Natural selection has no intelligence. It does not possess a will that can decide what is good and what is bad for living things. As a result, natural selection cannot explain how biological systems and organs that possess the feature of "irreducible complexity" came into being. These systems and organs are composed of a great number of parts working together, and are of no use if even one is missing or defective. The human eye cannot function unless it exists with all it's components intact. The will that brings all these parts together should be able to foresee the future and aim directly at the advantage that is to be acquired at the final stage. Since natural selection has no consciousness or will, it can do no such thing. This fact demolishes the foundations of the theory of evolution.

  22. So weak goofy people as yourself should have been faded out, if not for constitutional religious doctrine, that claims that even the weakest are created equal.

  23. Here's the rest of the title of origin of spiecies, " Preservation of Favoured Races in the Struggle for Life." They left that out by mistake I'm sure.

  24. All this heard, the question that always bugs me is why do organisms choose life? Even when they don't have any conceptual understanding of life or death…how and why do they adapt to live to on? To whom does it concern that they live on?

  25. I did not believe in God
    I hated his ways.
    But God changed me! God created this universe and all life started from him but we have sinned and we lost the purpose of God.
    I was addicted to alcohol, obscene, to pornography. This world today is full of adultery. Children hate parents, the younger generation no longer follows God.
    But do you know that God still loves us?
    Two years ago, I was so depressed. After the New Year's party, I got tired of this world. Then God came to me.
    God showed me that he was real.
    When we're all not even thinking about him, he's still waiting.
    I cried so much that I cry even now. This generation is really rejecting God. And there is a judgment coming. We all, like sheep, have gone astray, each of us has turned to our own way; and the Lord has laid on Jesus the iniquity of us all.
    Do you know that hell is real? God made us in his image but we use our functions to hate things, steal, lie, gossip! That's why we don't know God. But he is so near that if you seek him, you will find him just as he promised!

    The love of God cannot measure with ours. He gave us all. He sent his son Jesus Christ to die on the cross for my sin. And Jesus rose again! So you who are reading can be saved and become children of God! Jesus is the only way to be saved. Repent and believe him. God is giving us today to repent and return to him. He sent his son so we can live. We can be forgiven and begin everything clean through Jesus. We can even become a new creation and live with Jesus forever.

    Ask God to forgive you and reveal yourself. I know he will because I know he is real and he is with me. Heaven rejoices when a sinner returns to him. After giving my life completely to Jesus, all my addictions disappeared and I am living a new life. Now this world is nothing to me. Money, success, popularity … are just lies that the devil uses to make our mind lose consciousness and turn against God. God can take care of that if you seek his kingdom. That's not important. This is not religion. It's all about Jesus. It is if you know God and love him. That's very true. Jesus will come soon and everything that rebels against him will be judged. He still loves you. He wants you to come back. We have to change our lives! Thank you for reading.

  26. The theory is incorrect. You can't extrapolate macro evolution from micro evolution using natural selection. Natural selection is powerless to generate the vast amounts of precision coding necessary to create new body plans because it is entirely dependent on a random process…. namely random damage to the DNA. Rare beneficial mutations are environment dependent. It is by pure chance the damage is beneficial. Imagine designing a birds wing using this process. Good grief.

  27. Very helpful video, but I still don't understand how this proves anything about evolution (besides natural selection) because the moths weren't changing, it was just that the darker moths became more populated.

  28. Gentlemen, I don't mean to ruffle your "evolutionary feathers" here, but
    there are several leading scientific theories that cast serious doubts on the theory of macroevolution. The Chaos Theory questions the concept of adaptation to the environment
    driven by natural selection, implies that environment does not produce complex adaptations, and says that evolution is chaotic. The Punctuated Equilibrium Theory casts serious doubts on Darwinian gradualism. The Tangled Tree or Lateral Gene Transfer Theory casts serious doubts on the idea of Tree of life and splitting (speciation) that require only
    vertical gene transfer which is based on pure lineages/common ancestry.
    The Convergent Evolution Theory casts serious doubts on common
    ancestry. With all these problems, how can it be considered a fact?
    Why not mention all these scientific theories in the books of evolution?
    Why are these theories not presented as counter-theories? Why is
    evolution advertised as "the only theory" or as an “undeniable fact"
    when above theories have challenged many aspects of it? If evolutionists
    don't tell us about such counter-theories, they're making evolution
    look like a religion that turns blind eye to counter-theories. As it
    is, evolution is a work-in-progress at best.

  29. Cheese has holes. More cheese = more holes. More holes = less cheese. More cheese = less cheese.

  30. Let's not beat around the bush… macroevolution is a fantasy. New body plans acquired through natural selection?… which is what now? ….a slave to a random process? Good grief. The theory has devolved into an entity whose primary function is to eliminate the need for a creator. In order to accomplish this real science has been kicked to the curb and superseded by speculation and assumption. It is a great stain on the scientific community and an absolute disgrace this is still being taught in schools. I wonder what parents would think if they knew their children were, in actuality, being indoctrinated. Bacteria to Beethoven via the mutation lottery? C'mon. Evolutionists lack that all-important embarrassment gene.

  31. I've got an entrance exam on the same level as A-level, is this video series of A-level crash course helpful to at least get a 50? I NEED TO PASS!! T-T

  32. WALKING WHALES LIE; Pakicetus was a wolf like mammal. It had a bone in it's inner ear called an "involucrum" that resembled something found in whales. It was fully terrestrial (lived it's entire life on land) and looked nothing like a whale but neo-Darwinist, desperate for a whale ancestor, tagged it Pakicetus or "Pakistani whale". Ambulocetus, Maiacetus, Kuchicetus and Rodhocetus were extinct variations of sea lions or otters. They were amphibious (lived part of their lives on land and part in the water). They used their hind legs and tail for swimming and their four limbs for walking on land.
    Basilosaurus and Dorudon were extinct whales that were fully aquatic ( lived their entire lives in the water).
    Land and amphibious mammals have nostrils for breathing on the front of their heads. Whales have a blowhole on the top of their bodies to breath.
    The blowhole of a whale is surrounded by thick muscular “lips” that keep the hole tightly closed except when the animal makes a deliberate effort to open it at the surface. Total submersion thus takes less effort for whales than for animals that must actively exclude water from their air passages. Coming onto land is not a natural act for a whale; beached whales die if they're not quickly helped back in the water.
    Land and amphibious mammals use four legs—tail assisted for amphibians while in water—to move around in their environment. Whales use a fluke to move around in their environment. Land and amphibian mammals can survive without the tip of their tail. Whales can't survive without it.
    Flukes are flat horizontal lobes at the ends of their tails. Fluke movements are coordinated by a complex system of long, powerful tendons connecting them to specialized muscles in the tail.
    These are a few of the myriad of changes they would have to undergo. For neo-Darwinist it would take hundreds of millions of random mutations (random variations for traditional Darwinist), to compel a fully terrestrial mammal to turn into a fully aquatic mammal.
    The biggest problem for the "walking whales" is the empirical evidence–Darwinist refuse to acknowledge–not found in the fossil record. It's all but complete. Paleontologist have not discovered the fossils of innumerable transitional intermediate mammals, falling between and linking Pakicetus and whales. All the natural history museums in the world should be overflowing with them.
    With enough imagination anyone can invent a story about how land mammals evolved into whales. But an imaginative story isn't empirical science.

  33. I'd actually argue that peacock tails would be a great example of stabilizing selection. They need a big enough tail to attract the ladies, but not so huge that they can't move to find food or escape predators before they've had a chance to pass on their genes. Thoughts? Love this channel : ) -BOGO

  34. Natural selection is a slave to a random process,.. namely random copying errors of the DNA. This lacks the power to build body plans for every creature that ever lived. The mutation lottery took us from bacteria to Beethoven? Not in this universe. Just another propaganda video.

  35. Why then does our genome
    contain more old dead genes and redundant copies of genes than it does active
    genes? Why do we share with chimps similar sets of these pseudogenes, with the
    same locations in the genome and most of the same errors in those pseudogenes
    if we did not come from a common ancestor?

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