Name: _______________________________________________________________________________
Smithsonian Institute Human Evolution Timeline
Directions: Explore the timeline interactive and answer the questions below to learn more
about human evolution http://humanorigins.si.edu/evidence/human-evolution-timeline-interactive
1. Complete the table by hovering over the different milestones in human evolution.
Symbol Years Ago
Event
Description
Early humans lived near open areas and
dense woods. Their bodies enable them to
walk upright but still climb trees
Control of fire make cooking possible.
Cooking led to changes in the human diet,
socialization, and safety.
Larger more complex brains enable humans
to interact different and to survive a more
unpredictable environment.
Humans found they could control the
growth and breeding of certain plants and
animals, leading to farming and herding.
2. Click on one of the early species of humans. Does this species seem more “human” or does it seem
to resemble other primates? Explain.
3. “Homo” is the genus that includes modern humans. What are the 7 different species of homo that
have lived on earth?
a. __________________________
e. __________________________
b. __________________________
f.
__________________________
c. __________________________
g. __________________________
d. __________________________
4. How many different species of “homo” have lived at the same time as modern humans? ______
5. How many different species of “homo” have gone extinct? ______________________________
6. Click on one of the species of “homo” other than modern humans. In the space below describe this
species. What does it look like? When did it live? Where did it live? What is interesting about it?
7. Click on some of the earlier human ancestors. What do all of these seem to have in common? Do
you notice any differences in these species?
8. After clicking on many of the different ancestors of modern humans, on which continent did most
of them live? _______________________________________________________________
9. Which was the first species to leave Africa? Why do you think this species was able to migrate out
of Africa?
10. After exploring this timeline of human evolution, what surprised you? Why?
Human Evolution One-Pager Instructions
1. Use a black sheet of paper.
2. Include the title and author somewhere on the page.
3. Decide on a main idea or thought from the reading to base your one pager on. Put this in the
center of the page.
4. Include at least 2 Quotations from the text. Follow each quote with a note to yourself about
why the quotes are important to the reading.
5. Draw pictures or symbols that show the theme of the reading. (At least 3)
6. Identify any people who are important in the reading and why they are important.
7. List 4 main ideas from the reading.
8. Make a personal summary statement or reflection about what you read. In other words, what
do you think about the reading?
9. Color your one pager! (At least 4 colors, black and white don’t count as colors!)
Points Earned Criteria
/1
/2
Included Title and Author
Main Idea in the Center of the Page
/4
/6
2 Quotations and why they are important
3 pictures
/1
/4
Important people and why they are important
4 Main Ideas from the reading
/3
Personal Summary Statement
/4
At least 4 colors (not black and white)
/25
Total
Humans are still evolving—and we can watch it happen
By Elizabeth Pennisi May. 17, 2016 SCIENCE
Many people think evolution requires thousands or millions of years, but biologists know it can
happen fast. Now, thanks to the genomic revolution, researchers can actually track the
population-level genetic shifts that mark evolution in action—and they’re doing this in humans.
Two studies presented at the Biology of Genomes meeting here last week show how our
genomes have changed over centuries or decades, charting how since Roman times the British
have evolved to be taller and fairer, and how just in the last generation the effect of a gene that
favors cigarette smoking has dwindled in some groups.
“Being able to look at selection in action is exciting,” says Molly Przeworski, an evolutionary
biologist at Columbia University. The studies show how the human genome quickly responds to
new conditions in subtle but meaningful ways, she says. “It’s a game-changer in terms of
understanding evolution.”
Evolutionary biologists have long concentrated on the role of new mutations in generating new
traits. But once a new mutation has arisen, it must spread through a population. Every person
carries two copies of each gene, but the copies can vary slightly within and between individuals.
Mutations in one copy might increase height; those in another copy, or allele, might decrease
it. If changing conditions favor, say, tallness, then tall people will have more offspring, and more
copies of variants that code for tallness will circulate in the population.
With the help of giant genomic data sets, scientists can now track these evolutionary shifts in
allele frequencies over short timescales. Jonathan Pritchard of Stanford University in Palo Alto,
California, and his postdoc Yair Field did so by counting unique single-base changes, which are
found in every genome. Such rare individual changes, or singletons, are likely recent, because
they haven’t had time to spread through the population. Because alleles carry neighboring DNA
with them as they circulate, the number of singletons on nearby DNA can be used as a rough
molecular clock, indicating how quickly that allele has changed in frequency.
Pritchard’s team analyzed 3000 genomes collected as part of the UK10K sequencing project in
the United Kingdom. For each allele of interest in each genome, Field calculated a “singleton
density score” based on the density of nearby single, unique mutations. The more intense the
selection on an allele, the faster it spreads, and the less time there is for singletons to
accumulate near it. The approach can reveal selection over the past 100 generations, or about
2000 years.
Stanford graduate students Natalie Telis and Evan Boyle and postdoc Ziyue Gao found relatively
few singletons near alleles that confer lactose tolerance—a trait that enables adults to digest
milk—and that code for particular immune system receptors. Among the British, these alleles
have evidently been highly selected and have spread rapidly. The team also found fewer
singletons near alleles for blond hair and blue eyes, indicating that these traits, too, have
rapidly spread over the past 2000 years, Field reported in his talk and on 7 May in the preprint
server bioRxiv.org. One evolutionary driver may have been Britain’s gloomy skies: Genes for fair
hair also cause lighter skin color, which allows the body to make more vitamin D in conditions
of scarce sunlight. Or sexual selection could have been at work, driven by a preference for
blond mates.
Other researchers praise the new technique. “This approach seems to allow much more subtle
and much more common signals of selection to be detected,” says evolutionary geneticist
Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
In a sign of the method’s power, Pritchard’s team also detected selection in traits controlled not
by a single gene, but by tiny changes in hundreds of genes. Among them are height, head
circumference in infants, and hip size in females—crucial for giving birth to those infants. By
looking at the density of singletons flanking more than 4 million DNA differences, Pritchard’s
team discovered that selection for all three traits occurred across the genome in recent
millennia.
Joseph Pickrell, an evolutionary geneticist at New York Genome Center in New York City, has
used a different strategy to put selection under an even keener microscope, detecting signs of
evolution on the scale of a human lifetime. He and Przeworski took a close look at the genomes
of 60,000 people of European ancestry who had been genotyped by Kaiser Permanente in
Northern California, and 150,000 people from a massive U.K. sequencing effort called the UK
Biobank. They wanted to know whether genetic variants change frequency across individuals of
different ages, revealing selection at work within a generation or two. The biobank included
relatively few old people, but it did have information about participants’ parents, so the team
also looked for connections between parental death and allele frequencies in their children.
In the parents’ generation, for example, the researchers saw a correlation between early death
in men and the presence in their children (and therefore presumably in the parents) of a
nicotine receptor allele that makes it harder to quit smoking. Many of the men who died young
had reached adulthood in the United Kingdom in the 1950s, a time when many British men had
a pack-a-day habit. In contrast, the allele’s frequency in women and in people from Northern
California did not vary with age, presumably because fewer in these groups smoked heavily and
the allele did not affect their survival. As smoking habits have changed, the pressure to weed
out the allele has ceased, and its frequency is unchanged in younger men, Pickrell explains. “My
guess is we are going to discover a lot of these gene-by-environment effects,” Przeworski says.
Indeed, Pickrell’s team detected other shifts. A set of gene variants associated with late-onset
menstruation was more common in longer-lived women, suggesting it might help delay death.
Pickrell also reported that the frequency of the ApoE4 allele, which is associated with
Alzheimer’s disease, drops in older people because carriers died early. “We can detect selection
on the shortest timeframe possible, an individual’s life span,” he says.
Signs of selection on short timescales will always be prey to statistical fluctuations. But together
the two projects “point to the power of large studies to understand what factors determine
survival and reproduction in humans in present-day societies,” Pääbo says.