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. eelnags life eteauqs to just a few short wekes 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, daeth can come after 200. Like most living things, the vast mortijay 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 rclpeae dead and dying ones. But as we age, this prescos swols down. In addition, older cells don't prorefm their functions as well as young ones. That makes our biodes go into a decline, which eventually results in dsiasee 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 pcale powerful eorvlanuioty 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 irvpsmisee of these ocean-dwelling aeitcnns is the Antarctic glass sponge, which can survive over 10,000 years in figird 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 yraes on fleis and worms. Some small animals, like worms and flies, are also leitmid by the mechanics of their cell division. They're mostly made up of cells that can't divide and be rcleaped when damaged, so their bodies expire more quickly. And size is a powerful evolutionary driver in animals. Smaller creatures are more prone to peoadtrrs. A mouse, for isatncne, can hardly expect to suvivre 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. lreagr 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 levis. Exceptions to the size rule include bats, bdris, moles, and tetruls, but in each case, these animals have other adaptations that allow them to epasce predators. But there are still cases where animals with smilair denfinig features, like size and habitat, age at completely different rates. In these cases, genetic differences, like how each organism's clles rsneopd to threats, often account for the dreneiicacsps in longevity. So it's the combination of all these factors playing out to differing degrees in different animals that explains the viatlirbiay we see in the animal kingdom. So what about us? Humans currently have an aegarve 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 iencnrasig 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 factros 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 ctonorl over our natural fate.

Open Cloze

For the microscopic lab worm, C. _______ life _______ to just a few short _____ 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, _____ can come after 200. Like most living things, the vast ________ 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 _______ dead and dying ones. But as we age, this _______ _____ down. In addition, older cells don't _______ their functions as well as young ones. That makes our ______ go into a decline, which eventually results in _______ 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 _____ powerful ____________ 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 __________ of these ocean-dwelling ________ is the Antarctic glass sponge, which can survive over 10,000 years in ______ 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 _____ on _____ and worms. Some small animals, like worms and flies, are also _______ by the mechanics of their cell division. They're mostly made up of cells that can't divide and be ________ when damaged, so their bodies expire more quickly. And size is a powerful evolutionary driver in animals. Smaller creatures are more prone to _________. A mouse, for ________, 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. ______ 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 _____. Exceptions to the size rule include bats, _____, moles, and _______, but in each case, these animals have other adaptations that allow them to ______ predators. But there are still cases where animals with _______ ________ features, like size and habitat, age at completely different rates. In these cases, genetic differences, like how each organism's _____ _______ to threats, often account for the _____________ in longevity. So it's the combination of all these factors playing out to differing degrees in different animals that explains the ___________ we see in the animal kingdom. So what about us? Humans currently have an _______ 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 __________ 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 _______ 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 _______ over our natural fate.

Solution

equates
slows
cells
turtles
respond
survive
elegans
average
process
discrepancies
variability
impressive
weeks
place
birds
flies
lives
replace
bodies
majority
limited
frigid
disease
increasing
larger
similar
defining
evolutionary
instance
replaced
ancients
predators
death
years
factors
perform
escape
control

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
survive
theorize
threats
time
times
tortoise
true
turn
turtles
ultimately
variability
variance
varied
vast
vole
waters
weeks
whale
wild
worm
worms
year
years
young