Why do animals have such different lifespans? - Joao Pedro de Magalhaes

For the microscopic lab worm C. elegans, life equates to just a few short weeks on Earth. The bowhead whale, on the other hand, can live over two hundred years. Why are these lifespans so different? And what does it really mean to ‘age' anyway? Joao Pedro de Magalhaes explains why the pace of aging varies greatly across animals.

Lesson by Joao Pedro de Magalhaes, animation by Sharon Colman.

[ShadowEvertide]

I wish they had talked about how crazy bird life expectancies are. Little birds only live 2-4 years but parrots like cockatoos have a life expectancy of 80-100 years. It's really interesting

[Parker_Miller_M.S.]

This guys voice is the best, if he can do every educational video ever that would be great.

[elliesmith]

One day people will be like " ONLY 71 YEARS?!" "THAT'S SO SHORT!"

[ComedyWorldNews]

When the girl in the animation pulls her leg back at the end, i briefly thought she was going to kick the guy in the nuts 😭

[Crazould]

"we are the only species on earth to take control over our natural fate "
wow that's deep

[TodunOlusola]

feels kind of depressing knowing I will start degenerating in a few years.

[RoyalDuckreal]

Me when i see ted new video i havent seen before : *its time to learn everything and nothing at the same time*

[immersiveparadox]

You forgot the *Legends*

*Legends* _never die._

[TheLoongsiu]

if human can live up to 400 years, the world will end way more quickly.

[thinker]

But what if we could engineer our telomeres so that they don't get shorter as we age?

[patriciasiswandjo]

This is really nice. I was hoping you guys can do a video on why certain dog breeds live longer than others!

[AlasdairGR]

2:34 I don’t know why, but that freaked me out.

[elsabella]

You know...this gives an added perspective to existentialism. Knowing that a clam/shell creature will outlive me really makes me wonder why I exist at all. Would it be better if I was a clam/shell? Maybe

[meribarseghyan]

This has interested me for a long time. As I heard that the average lifespan for some animals was different. It is really interesting how whales can live on average for 200 years.
I really liked the part where you said "We are the only species on earth to take control over our natural fate ". Imagine if one day we will be able to make average life even longer like 150 years.

[Teajonmustard]

Isn’t it weird that dying at age 50 is young, but you are arguably old at age 50?

[fayedingle]

I love how the guys shirt at the end said *notification squad*

[hmmjhcj]

lol those elephants are cute, wiggling their trunks back and forth xD

[nemorulz]

The only thing I learned from this is why Peter griffin lives in Quahog and drinks at the drunken clam

[alexanderx]

0:33 Salmon: Imma speed run that part.

[Elliandr]

You missed an extremely important fact, and got another one completely backwards. Experiments on a fly with an life expectancy of 24 hours pushed that to 72 hours simply by delaying the point of reproduction. It was hypothesized that the individual is useless to nature once reproduction has been carried out. In the case of the Fly, they are programmed to die shortly after reproduction, but when this is consistently delayed the epigenetic markers pushed that out to ensure that the next generation is able to survive long enough to reproduce. In this way, the mouse doesn't reproduce fast because it has a short life span - it has a short life span because it reproduces fast. Nature has selected for fast reproducing mice because those who wait have a higher likelihood of being eaten. While this may sound like a case of fast reproduction in response to early death, keep in mind that we are talking about natural death - aging - being influenced by being killed via outside forces.

Similar trends are observable in recorded human history. In eras and locations where war and famine had a higher tendency to kill people at a young age, reproduction occurred even younger, which in turn sped up the rate of sexual maturity. It is even biologically possible for a human of just a few years old to give birth to a health baby, as has actually happened. Hypothetically speaking, if some selective pressure pushed for that, humans could rapidly change to have the lifespan of mice. Of course, with modern humans, the push for education has resulted in cultural delays on reproduction with the age of sexual consent being pushed up to a higher age faster than nature can keep up. This has resulted in a teen pregnancy statistic - something humans have never even cared about before - which is still on average higher than the age humans used to reproduce on average. There are still outliers though, like the 12 year old girl who has a baby who herself was born when her mother was 12 making the youngest grandmother in the UK, but as a whole, despite the biological push to reproduce at a younger age than culture allows, humans are consciously choosing to wait, with an even larger population waiting until their 30's and 40's to have children than ever before. All of this tells us that the gradually increasing lifespan has more to do with epigenetics than modern medical science.

Not that modern medical science isn't also playing a role, but it's actually a long term negative. Or rather it will be until human gene therapy can tackle the resulting issues. You see, many humans have genetic defects that are easier to pass on when modern medical science helps them to live to the point of sexual maturity. Most people think of the age related conditions, but I argue that's a smaller issue since it's connected to aging - not age. As the rate of human aging adjusts these conditions should, at least in principle, change the age at which they appear.

After so many generations of epigenetic stability, the process eventually becomes hard coded. People think of random mutation when they think of evolution, but that's rarely the cast. Most mutations tend to be harmful. Hard coding of an epigenetic change happens because the epigenome changes what genes are being coded and so when a mutation happens in a non coded region it being impossible to change back without another mutation. A good example of this is the teeth of a chicken, who still have the genes for sharp teeth, but can no longer escape from the egg when an epigenetic change otherwise results in the formation of teeth since another important gene is broken. A mutation can bring it back, but only if the mutation coincides with the epigenetic change.

To those who doubt how important the epigenome is to evolution, consider this: The placenta is viral. Or rather, the ancestor of all mammals was infected with a retrovirus at the point of conception which caused the virus to spread evenly to all cells (the only way to pass a virus on reproductively as part of the species genome) and the epigenome later on figured out how to turn the virus genes on and off at precise times to create the placenta. In fact, a fair chunk of human DNA is viral in origin, and all of which controlled epigenetically. You simply cannot form a factual basis for explaining life without looking at this system. It's the real time adaptation level that really enables species to adapt to their environment.