|Can you explain human evolution?|
|Question Date: 2018-02-08|
That's a big question, but evolution works
about the same in all living things. Generally, it
happens as a result of natural select.
Individuals in a species are genetically
different from each other (unless they're clones).
Some of the differences give an advantage that
allows those individuals to leave more offspring,
which then have the genes of their parents. Over
time, the helpful genes become more common. The
differences between individuals are the result of
random mutation. The selection part is
In humans, some of the trends that gave
individuals an advantage seem to be increased
brain size, walking more upright (which allows
hands to be less foot-like), and a mostly hairless
body. Individuals with random mutations that gave
them these characteristics were more likely to
We are not descended from chimps, gorillas,
monkeys, or any other living primate, but
we share a primate ancestor that had opposable
thumbs. The descendants of the first primates
split over millions of years into many different
types of primates. Some are extinct. Some are
still around. The first humans evolved about
200,000 years ago, but there were other lines
that had some of our characteristics but died out.
Why do you think humans are so successful
while our closest relatives are often threatened
Thanks for asking,
Thanks for the great question!
While many people before him thought animals
change and evolve over time, it was Charles
Darwin who determined how evolution works.
Darwin’s idea is called evolution by natural
selection. Animals of the same species, Darwin
(1) have to compete to survive,
(2) exhibit variation (in size, coloration,
behavior, etc.), and
(3) pass down their traits to their offspring.
It was those animals that fit best in their
environment that were able to survive and
reproduce the most, and so the traits of those
fit individuals spread throughout a species. Over
time, certain traits die out and others survive.
With the accumulation of new traits, entire new
species evolve. Hundreds of years of research,
especially modern genetics, have since
supported and elaborated on Darwin’s original
Humans are a result of evolution by natural
selection . Biological anthropologists and
evolutionary psychologists, including those at UC
Santa Barbara, study human evolution .
About six million years ago in Africa, due to
the changing climate at the time, the ancestor of
modern humans split from the linage that would
eventually evolve into the chimpanzee. These human
ancestors were unique in that they were bipedal,
they walked primarily on two legs, and had
increasingly larger brains for the size of their
bodies. These early human ancestors include
Homo habilis, the first to use tools, and
Homo erectus, who spread out across the
world about two million years ago. H. erectus
used tools and fire and lived on Earth until only
140,000 years ago!
Anatomically modern humans, Homo sapiens,
evolved from the same linage of these ancestors
about 200,000 years ago. Humans quickly
migrated out of Africa and colonized the
world, reaching as far as islands in the
middle of the Pacific Ocean some 50,000 years ago.
Other species of the genus Homo, like the
Neanderthals in Europe and Eurasia, went quickly
extinct with the arrival of H. sapiens ,
likely because of modern human’s superior
intelligence and communication abilities. Humans
evolved to exploit their environment using their
brains, and eventually, human brains started
creating culture, science, art, agriculture,
civilization, and all the rest.
Thanks again for the great question,
Human evolution is the process by which modern
humans (us) have come from our ancestor organisms
through many years of adapting to our
environments. To become Homo sapiens, our
entire bodies have changed from the DNA-level
up. Not only have our genes themselves
changed, but how they turn into RNA (cellular
messengers) and proteins (cellular machinery) has
changed, too. It is a slow but fascinating process
because as different as we look and behave from
other animals such as chimpanzees, only about
1% of our genome (complete set of genes) is
different from the genome of the chimpanzee!
This small difference simultaneously showcases the
essential components of life (the high percent
similarity) AND the subtle cellular and organismal
adaptations that go far beyond simple changes in
The theory of evolution (with high volumes
of compelling evidence) indicates that
adapting to our environments in order to become
the humans we now are required long periods of
exposure to these environments, and many
iterations of the selection processes in which the
organisms that can most quickly begin to use their
environments in the best ways live longer and
produce offspring that then propagate. The
organisms that do not adapt as quickly or readily
eventually give way to the optimal organisms, and
that is how we modern humans came to be.
However, as supported as the theory is by
evidence, many questions remain as to how exactly
we became humans - scientists are actively
studying all steps leading from simple single-cell
organisms to humans.
I could probably keep explaining human evolution
for most of the rest of my life. Part of the
reason it would take so long is that new
research keeps discovering new things about human
evolution, so then I'd need to add that new
research to my explanation.
One thing I learned recently about human
evolution is about Vitamin C. I thought that all
the animals except humans and guinea pigs could
make their own Vitamin C; the other animals don't
need to eat it as a vitamin. But it turns out
that non-human primates also don't make their
own Vitamin C, which fits with the fact that we
and the non-human primates share a common
ancestor. That common ancestor was probably
a primate that lost the ability to make its own
Vitamin C. Some ancestor of guinea pigs probably
also lost the ability to make its own Vitamin C.
But other rodents can make their own Vitamin C, so
the guinea pig ancestor that lost the ability to
make its own Vitamin C must have been an ancestor
of the guinea pig but not an ancestor other
Guinea pigs are domesticated animals that
descended from some guinea-pig like rodent in the
Andes in South America. I wonder if the wild
ancestor of the guinea pig needs vitamin C. I
could probably find out if I looked hard enough on
the internet, but I'll not do that now.
I'll suggest that you google 'human evolution'
and read what Wikipedia and some of the other
links say. I hope you find what you want!
Only partially - there is a lot that we still
Humans are members of a family of apes called
the Homonidae, which includes modern humans (Homo
sapiens), chimpanzees (Pan troglodytes), bonobos
(Pan bonobo), and two species in the genus
Gorilla (I do not know if either of them have
common names apart from just "gorillas"). There
are also a great many extinct species in this
Humans shared an ancestor with chimpanzees
and bonobos between five and ten million years
ago. What this means is that there was a
species of ape at that time that had two
populations, and today's chimps and bonobos are
descended from one and humans are descended from
the other. That species of ape was neither a chimp
nor a bonobo nor a human; it was another species
of ape that is now extinct.
The population that gave rise to humans gave
rise to many, many species, all of them are now
extinct apart from H. sapiens. Of the line
that became H. sapiens, they appear to have
developed a roughly modern upright walking posture
by 3.5 million years ago, but did not
develop a modern brain size until about one
million years ago. By a million years ago, an
animal that could have had children with a modern
human certainly existed, because that's when the
population that would become H. sapiens and the
population that would become H. neanderthalensis
(neanderthals) diverged, and people of European
descent (i.e. white people) have about 4%
neanderthal ancestry. Neanderthals and other
human-like species at the time were probably about
as intelligent as modern humans, so why they
became extinct is a mystery.
Humans are still evolving .
Unfortunately, we seem to be evolving in a
direction that we would rather not go: more
intelligent people are having fewer children than
less intelligent people, and as a result humans
are over time becoming less intelligent. The
reason for this trend is probably social. This
will probably lead to our extinction if we don't
do something to counteract it (or unless something
else causes us to become extinct first, such as
war or damage to the environment).
First, it is important to note that humans
are not descended from apes. Rather apes and
humans have a common ancestor that existed
millions of years ago. It is a misconception
to think of this ancestor as a “missing link”
along a straight lineage from apes to humans,
but rather the ancestor is a node where the ape
lineage and human lineage branched off into
Human beings (Homo sapiens) evolved from
now-extinct primates sometime around
200,000-300,000 years ago. Humans are the
only surviving species of the genus Homo
but there is abundant evidence in the fossil
record to suggest that humans were preceded for
millions of years by other members of the
subfamily called hominins (now all extinct
except for humans) which have various human-like
characteristics and co-existed with humans for at
least for some time.
Human evolution is pretty complicated but here I
will try and provide a very brief timeline of
major events in human evolution (the dates
500 million years ago Evolution of the
vertebrates - The early vertebrates are the
ancestors of all fish, amphibians, birds,
reptiles, and mammals. The distinguishing
feature of vertebrates is a backbone which
basically makes it possible for vertebrates to
have a nerve cord running along the length of the
animal and providing a central nervous system.
400 million years ago The rise of the tetrapods
(four-limbed vertebrates) - The first
tetrapods were aquatic but eventually moved onto
land and are the ancestors of amphibians,
reptiles, birds, and mammals.
300 million years ago Amniote evolution -
The next major evolutionary event was the
development of the amniotic egg, and allowed
reptiles to move farther onto land, away from the
65 million years ago – 1.6 million years ago
explosion of mammals. Major developments in
mammalian evolution include the evolution of
placental mammals which can give birth to live
young. Earliest primates also evolved during
13 million years ago – Pierolapithecus
catalaunicus is the last known common ancestor of
all apes and humans.
pierolapithecus catalaunicus .
5.5 million years ago -humans and chimpanzees
split from unknown common ancestor [S. Kumar,
A. Filipski, V. Swarna, A. Walker and S. B. Hedges
PNAS 2005 December, 102 (52) 18842-18847.
5-2.6 million years ago early hominins -
proto-humans develop. The most important of
these is genus Australopithecus, which had a
brain-size similar to a chimpanzee.
2 million years ago Homo habilis -
developed from Australopithecus, had some advanced
human-like traits. Homo habilis is considered
to be the first of genus Homo (man-like)
homo habilis .
1.8 million years ago –Homo erectus –
human-like body features and used primitive tools,
homo erectus .
400,000 – 40,000 years ago Neanderthals (Homo
neanderthaensis) appear in fossil record.
Neanderthals populated Europe and parts of Asia
and used tools. Humans are not descended from
Neanderthals, but they are the closest extinct
relative to modern humans.
200,000 years ago first appearance of humans
(homo sapiens) in Africa. However, at this
point they had not developed art, sophisticated
hunting skills, or fishing.
60,000 years ago – “great leap forward” major
development in cognitive ability characterized by
abstract thinking. Innovation of jewelry,
painting, and advanced stone tools, possibly due
to vocal box developed or increase in brain size.
great leap forward
Humans migrate out of Africa into China and
45,000 years ago – humans spread across Europe
– Neanderthals soon disappear. (cave paintings
appear, statues , musical instruments).
15,000 years ago modern humans walk the Bering
land bridge and rapidly populate Americas.
11,000 years ago – agriculture develops.
5000 years ago – writing is invented, beginning
of recorded history.
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