TedTest

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

Unscramble the Blue Letters

For the mrciocosipc 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 yraes, 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 saxuel maturity in the process known as aging. But what does it really mean to age? The direvrs behind this process are varied and complicated, but aging is utitllmaey caused by cell death and dysfunction. When we're young, we constantly regenerate cells in odrer to replace dead and dying ones. But as we age, this process slows down. In addition, oeldr cells don't pfrorem their functions as well as young ones. That makes our bodies go into a decline, which eaeltuvnly 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 awnesr lies in several factors, iindcnlug environment and body size. These can place powerful evolutionary pressures on animals to adapt, which in turn makes the agnig poscers different across species. Consider the cold dtephs 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 gslas sponge, which can survive over 10,000 years in frigid wrteas. In cold environments like these, haetabtres and metabolic rteas slow down. Researchers theorize that this also causes a snwoilg of the aging process. In this way, the environment sheaps longevity. When it comes to size, it's often, but not always, the case that larger sciepes 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 bdioes expire more quickly. And size is a powerful evolutionary dvrier in animals. selamlr creatures are more prone to predators. A mouse, for instance, can hardly expect to suvrive 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 siezs and reproduce multiple times during their lives. Exceptions to the size rule include bats, brids, moles, and turtles, but in each case, these animals have other adaptations that allow them to escape parodrets. But there are still cseas where ainmlas 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 taerths, often aoccunt for the discrepancies in lotgveniy. So it's the combination of all these factors piynalg 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 ecnacxtpey of 71 years, meaning that we're not even clsoe to being the longest living inhabitants on Earth. But we are very good at increasing our life expectancy. In the early 1900s, hmnaus only lievd 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.

Open Cloze

For the ___________ 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 _____, 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 aging. But what does it really mean to age? The _______ behind this process are varied and complicated, but aging is __________ caused by cell death and dysfunction. When we're young, we constantly regenerate cells in _____ to replace dead and dying ones. But as we age, this process slows down. In addition, _____ cells don't _______ their functions as well as young ones. That makes our bodies go into a decline, which __________ 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 ______ lies in several factors, _________ environment and body size. These can place powerful evolutionary pressures on animals to adapt, which in turn makes the _____ _______ different across species. Consider the cold ______ 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 _____ sponge, which can survive over 10,000 years in frigid ______. In cold environments like these, __________ and metabolic _____ slow down. Researchers theorize that this also causes a _______ of the aging process. In this way, the environment ______ longevity. When it comes to size, it's often, but not always, the case that larger _______ 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 ______ expire more quickly. And size is a powerful evolutionary ______ in animals. _______ creatures are more prone to predators. A mouse, for instance, can hardly expect to _______ 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 _____ and reproduce multiple times during their lives. Exceptions to the size rule include bats, _____, moles, and turtles, but in each case, these animals have other adaptations that allow them to escape _________. But there are still _____ where _______ 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 _______, often _______ for the discrepancies in _________. So it's the combination of all these factors _______ 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 __________ of 71 years, meaning that we're not even _____ to being the longest living inhabitants on Earth. But we are very good at increasing our life expectancy. In the early 1900s, ______ only _____ 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.

Solution

ultimately
survive
smaller
humans
sexual
expectancy
slowing
microscopic
waters
lived
threats
older
account
longevity
predators
years
animals
rates
close
species
sizes
driver
shapes
eventually
bodies
answer
drivers
birds
glass
cases
process
order
including
playing
heartbeats
perform
depths
aging

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
bats
birds
bodies
body
bowhead
case
cases
caused
cell
cells
clam
close
cold
combination
compare
completely
complicated
consistently
constantly
contrast
control
creatures
damaged
dead
death
deaths
decline
defense
defining
degenerate
degrees
depths
differences
differing
discrepancies
disease
divide
division
driver
drivers
dying
dysfunction
early
earth
elegans
elephant
environment
environmental
environments
equates
escape
eventually
evolutionary
evolved
exceptions
expect
expectancy
expire
explains
exposure
factors
fate
features
fending
flies
frigid
functions
genetic
glass
good
gradually
greenland
grow
habitat
heartbeats
huge
humans
impressive
include
including
increases
increasing
inhabitants
instance
kingdom
lab
large
larger
learned
lies
life
lifespan
limited
live
lived
lives
living
longer
longest
longevity
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
seas
sexual
shapes
sharks
short
shorter
similar
size
sizes
slow
slowing
slows
small
smaller
species
sponge
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time
times
tortoise
true
turn
turtles
ultimately
variability
variance
varied
vast
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