TedTest

From the Ted Talk by Joao Pedro de Magalhaes: Why do animals have such different lifespans?

Unscramble the Blue Letters

For the microscopic lab worm, C. elegans life equates to just a few short weeks on Earth. Compare that with the tortoise, which can age to more than 100 years. Mice and rats reach the end of their lives after just four years, while for the bowhead whale, Earth's longest-lived mammal, death can come after 200. Like most living things, the vast majority of animals gradually degenerate after reaching sxaeul maturity in the process known as aigng. But what does it really mean to age? The drivers behind this process are varied and complicated, but aging is ultimately caused by cell detah and dysfunction. When we're young, we constantly regenerate clels in order to replace dead and dying ones. But as we age, this process slows down. In addition, older cells don't perform their functions as well as ynoug ones. That makes our bideos go into a decline, which eventually results in disease and death. But if that's consistently true, why the huge variance in aging patterns and lifespan within the animal kingdom? The answer lies in several factors, iduncinlg environment and body size. These can place powerful evolutionary pressures on animals to adapt, which in turn makes the aging pcreoss different across species. Consider the cold depths of the Atlantic and Arctic Seas, where Greenland sharks can live to over 400 years, and the Arctic clam known as the quahog can live up to 500. Perhaps the most ipvsesirme of these ocean-dwelling ancients is the Antarctic glass sngpoe, which can survive over 10,000 years in frigid waters. In cold environments like these, heartbeats and metabolic rates slow down. Researchers treizohe that this also causes a slowing of the aging process. In this way, the environment shapes longevity. When it comes to size, it's often, but not always, the case that lrgear species have a longer lifespan than smllaer ones. For inctsnae, an elephant or whale will live much longer than a mouse, rat, or vole, which in turn have years on files and worms. Some small animals, like worms and flies, are also limited by the mechanics of their cell division. They're mostly made up of cells that can't divide and be replaced when damaged, so their bodies expire more quickly. And size is a powerful evolutionary driver in aimalns. Smaller creatures are more prone to predators. A msoue, for instance, can hardly expect to survive more than a year in the wild. So, it has evvleod to grow and reproduce more rapidly, like an evolutionary deefnse mechanism against its shorter lesapifn. Larger animals, by contrast, are better at fending off predators, and so they have the lruuxy of time to grow to large sizes and reproduce mpiltule times during their lives. Exceptions to the size rule include bats, birds, moles, and turtles, but in each case, these animals have other adaptations that allow them to escape predators. But there are still cases where animals with similar defining fteueras, like size and hiaabtt, age at clelmtepoy different retas. In these cases, genetic diffecnrees, like how each organism's cells respond to threats, often anccout for the discrepancies in longevity. So it's the combination of all these factors playing out to diefnrifg degrees in different animals that explains the vaitiilarby we see in the animal kingdom. So what about us? Humans currently have an average life expectancy of 71 years, meaning that we're not even close to being the longest living itihabtnans on etrah. But we are very good at iicsnnreag our life eaxcectpny. In the early 1900s, hmanus only lived an average of 50 years. Since then, we've lrneaed to apdat by mnaginag many of the factors that cause dathes, like environmental exposure and nutrition. This, and other increases in life expectancy make us possibly the only species on Earth to take control over our natural fate.

Open Cloze

For the microscopic lab worm, C. elegans life equates to just a few short weeks on Earth. Compare that with the tortoise, which can age to more than 100 years. Mice and rats reach the end of their lives after just four years, while for the bowhead whale, Earth's longest-lived mammal, death can come after 200. Like most living things, the vast majority of animals gradually degenerate after reaching ______ maturity in the process known as _____. But what does it really mean to age? The drivers behind this process are varied and complicated, but aging is ultimately caused by cell _____ and dysfunction. When we're young, we constantly regenerate _____ in order to replace dead and dying ones. But as we age, this process slows down. In addition, older cells don't perform their functions as well as _____ ones. That makes our ______ go into a decline, which eventually results in disease and death. But if that's consistently true, why the huge variance in aging patterns and lifespan within the animal kingdom? The answer lies in several factors, _________ environment and body size. These can place powerful evolutionary pressures on animals to adapt, which in turn makes the aging _______ different across species. Consider the cold depths of the Atlantic and Arctic Seas, where Greenland sharks can live to over 400 years, and the Arctic clam known as the quahog can live up to 500. Perhaps the most __________ of these ocean-dwelling ancients is the Antarctic glass ______, which can survive over 10,000 years in frigid waters. In cold environments like these, heartbeats and metabolic rates slow down. Researchers ________ that this also causes a slowing of the aging process. In this way, the environment shapes longevity. When it comes to size, it's often, but not always, the case that ______ species have a longer lifespan than _______ ones. For ________, an elephant or whale will live much longer than a mouse, rat, or vole, which in turn have years on _____ and worms. Some small animals, like worms and flies, are also limited by the mechanics of their cell division. They're mostly made up of cells that can't divide and be replaced when damaged, so their bodies expire more quickly. And size is a powerful evolutionary driver in _______. Smaller creatures are more prone to predators. A _____, for instance, can hardly expect to survive more than a year in the wild. So, it has _______ to grow and reproduce more rapidly, like an evolutionary _______ mechanism against its shorter ________. Larger animals, by contrast, are better at fending off predators, and so they have the ______ of time to grow to large sizes and reproduce ________ times during their lives. Exceptions to the size rule include bats, birds, moles, and turtles, but in each case, these animals have other adaptations that allow them to escape predators. But there are still cases where animals with similar defining ________, like size and _______, age at __________ different _____. In these cases, genetic ___________, like how each organism's cells respond to threats, often _______ for the discrepancies in longevity. So it's the combination of all these factors playing out to _________ degrees in different animals that explains the ___________ we see in the animal kingdom. So what about us? Humans currently have an average life expectancy of 71 years, meaning that we're not even close to being the longest living ___________ on _____. But we are very good at __________ our life __________. In the early 1900s, ______ only lived an average of 50 years. Since then, we've _______ to _____ by ________ many of the factors that cause ______, like environmental exposure and nutrition. This, and other increases in life expectancy make us possibly the only species on Earth to take control over our natural fate.

Solution

variability
multiple
lifespan
young
process
completely
luxury
humans
increasing
adapt
managing
death
differences
mouse
bodies
flies
account
theorize
including
cells
expectancy
animals
features
differing
learned
impressive
habitat
smaller
earth
larger
instance
aging
sexual
deaths
inhabitants
rates
sponge
defense
evolved

Original Text

For the microscopic lab worm, C. elegans life equates to just a few short weeks on Earth. Compare that with the tortoise, which can age to more than 100 years. Mice and rats reach the end of their lives after just four years, while for the bowhead whale, Earth's longest-lived mammal, death can come after 200. Like most living things, the vast majority of animals gradually degenerate after reaching sexual maturity in the process known as aging. But what does it really mean to age? The drivers behind this process are varied and complicated, but aging is ultimately caused by cell death and dysfunction. When we're young, we constantly regenerate cells in order to replace dead and dying ones. But as we age, this process slows down. In addition, older cells don't perform their functions as well as young ones. That makes our bodies go into a decline, which eventually results in disease and death. But if that's consistently true, why the huge variance in aging patterns and lifespan within the animal kingdom? The answer lies in several factors, including environment and body size. These can place powerful evolutionary pressures on animals to adapt, which in turn makes the aging process different across species. Consider the cold depths of the Atlantic and Arctic Seas, where Greenland sharks can live to over 400 years, and the Arctic clam known as the quahog can live up to 500. Perhaps the most impressive of these ocean-dwelling ancients is the Antarctic glass sponge, which can survive over 10,000 years in frigid waters. In cold environments like these, heartbeats and metabolic rates slow down. Researchers theorize that this also causes a slowing of the aging process. In this way, the environment shapes longevity. When it comes to size, it's often, but not always, the case that larger species have a longer lifespan than smaller ones. For instance, an elephant or whale will live much longer than a mouse, rat, or vole, which in turn have years on flies and worms. Some small animals, like worms and flies, are also limited by the mechanics of their cell division. They're mostly made up of cells that can't divide and be replaced when damaged, so their bodies expire more quickly. And size is a powerful evolutionary driver in animals. Smaller creatures are more prone to predators. A mouse, for instance, can hardly expect to survive more than a year in the wild. So, it has evolved to grow and reproduce more rapidly, like an evolutionary defense mechanism against its shorter lifespan. Larger animals, by contrast, are better at fending off predators, and so they have the luxury of time to grow to large sizes and reproduce multiple times during their lives. Exceptions to the size rule include bats, birds, moles, and turtles, but in each case, these animals have other adaptations that allow them to escape predators. But there are still cases where animals with similar defining features, like size and habitat, age at completely different rates. In these cases, genetic differences, like how each organism's cells respond to threats, often account for the discrepancies in longevity. So it's the combination of all these factors playing out to differing degrees in different animals that explains the variability we see in the animal kingdom. So what about us? Humans currently have an average life expectancy of 71 years, meaning that we're not even close to being the longest living inhabitants on Earth. But we are very good at increasing our life expectancy. In the early 1900s, humans only lived an average of 50 years. Since then, we've learned to adapt by managing many of the factors that cause deaths, like environmental exposure and nutrition. This, and other increases in life expectancy make us possibly the only species on Earth to take control over our natural fate.

Frequently Occurring Word Combinations

ngrams of length 2

collocation	frequency
life expectancy	3
powerful evolutionary	2
aging process	2

Important Words

account
adapt
adaptations
addition
age
aging
ancients
animal
animals
answer
antarctic
arctic
atlantic
average
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birds
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body
bowhead
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cases
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cells
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cold
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compare
completely
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consistently
constantly
contrast
control
creatures
damaged
dead
death
deaths
decline
defense
defining
degenerate
degrees
depths
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differing
discrepancies
disease
divide
division
driver
drivers
dying
dysfunction
early
earth
elegans
elephant
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environmental
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escape
eventually
evolutionary
evolved
exceptions
expect
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expire
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exposure
factors
fate
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frigid
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genetic
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good
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greenland
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kingdom
lab
large
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learned
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lifespan
limited
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lived
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living
longer
longest
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luxury
majority
mammal
managing
maturity
meaning
mechanics
mechanism
metabolic
mice
microscopic
moles
mouse
multiple
natural
nutrition
older
order
patterns
perform
place
playing
possibly
powerful
predators
pressures
process
prone
quahog
quickly
rapidly
rat
rates
rats
reach
reaching
regenerate
replace
replaced
reproduce
researchers
respond
results
rule
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sexual
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sharks
short
shorter
similar
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sizes
slow
slowing
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true
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