Our human ancestors walked on two feet but their children still had a backup plan

July 4, 2018, Dartmouth College
The Dikika foot is one part of a partial skeleton of a 3.32 million-year-old skeleton of an Australopithecus afarensis child. Credit: Zeray Alemseged

More than 3 million years ago, our ancient human ancestors, including their toddler-aged children, were standing on two feet and walking upright, according to a new study published in Science Advances.

"For the first time, we have an amazing window into what walking was like for a 2½-year-old, more than 3 million years ago," says lead author, Jeremy DeSilva, an associate professor of anthropology at Dartmouth College, who is one of the world's foremost authorities on the feet of our . "This is the most complete of an ancient juvenile ever discovered."

The tiny foot, about the size of a human thumb, is part of a nearly complete 3.32-million-year-old skeleton of a young female Australopithecus afarensis discovered in 2002 in the Dikika region of Ethiopia by Zeresenay (Zeray) Alemseged, a professor of organismal biology and anatomy at the University of Chicago and senior author of the study. Alemseged is internationally known as a leading paleontologist on the study of human origins and human evolution.

"Placed at a critical time and the cusp of being human, Australopithecus afarensis was more derived than Ardipithecus (a facultative biped) but not yet an obligate strider like Homo erectus. The Dikika foot adds to the wealth of knowledge on the mosaic nature of hominin skeletal evolution" explained Alemseged.

The 3.32 million-year-old Australopithecus afarensis foot from Dikika, Ethiopia, superimposed over a footprint from a human toddler. Credit: Jeremy DeSilva

Given that the fossil of the tiny foot is the same species as the famous Lucy fossil and was found in the same vicinity, it is not surprising that the Dikika child was erroneously labeled "Lucy's baby" by the popular press, though this youngster lived more than 200,000 years before Lucy.

In studying the fossil foot's remarkably preserved anatomy, the research team strived to reconstruct what life would have been like years ago for this toddler and how our ancestors survived. They examined what the foot would have been used for, how it developed and what it tells us about . The indicates that these ancient ancestors were quite good at walking on two legs. "Walking on two legs is a hallmark of being human. But, walking poorly in a landscape full of predators is a recipe for extinction," explained DeSilva.

Left block of images: The 3.32 million year old foot from an Australopithecus afarensis toddler shown in different angles. Right block of images: The child's foot (bottom) compared with the fossil remains of an adult Australopithecus foot (top). Credit: Jeremy DeSilva & Cody Prang

At 2½ years old, the Dikika child was already walking on two legs, but there are hints in the fossil foot that she was still spending time in the trees, hanging on to her mother as she foraged for food. Based on the skeletal structure of the child's foot, specifically, the base of the big toe, the kids probably spent more time in the trees than adults. "If you were living in Africa 3 million years ago without fire, without structures, and without any means of defense, you'd better be able get up in a tree when the sun goes down," added DeSilva. "These findings are critical for understanding the dietary and ecological adaptation of these species and are consistent with our previous research on other parts of the skeleton especially, the shoulder blade," Alemseged noted.

Explore further: Lucy and Selam's species climbed trees

More information: J.M. DeSilvaat Dartmouth College in Hanover, NH el al., "A nearly complete foot from Dikika, Ethiopia and its implications for the ontogeny and function of Australopithecus afarensis," Science Advances (2018). advances.sciencemag.org/content/4/7/eaar7723

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24 comments

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gwrede
4.2 / 5 (5) Jul 04, 2018
"... the kids probably spent more time in the trees than adults."

Hmm. That's true even today, wherever there are climbable trees.
rrwillsj
2.3 / 5 (3) Jul 04, 2018
Instead of calling it "Lucy's Baby"?
We should be calling it "Lucy's Granny"?
Surveillance_Egg_Unit
2.1 / 5 (7) Jul 05, 2018
Homo species were all experimental models that became extinct before the creation of Homo Sapiens, except for Neanderthalensis who were contemporaries with humans and were known to have mated and bred with H.Sapiens. Researchers persist in their claims that H.Sapiens descended from Australopithecus, H.Ergaster, H.Erectus, H.Floriensis and any other comparatively similar species with humans. And yet, these researchers insist that humans share an ancestor with apes, where humans progressed mentally and physiologically while apes remained pretty much the same even after the alleged split-off from ape or ape-like ancestors.

Mammals, including the ape-like and ape species had already existed long before the creation of the first humans, who had been created as they appear now and with very little evolutionary change. So, if humans descended from such as H.Erectus, etc., then why do we share DNA with chimps, bonobos and gorillas? Any DNA available from H.Erectus to compare with humans?
humy
4.5 / 5 (8) Jul 05, 2018
if humans descended from such as H.Erectus, etc., then why do we share DNA with chimps, bonobos and gorillas?

Because chimps, bonobos, gorillas and H.Erectus all share a common (ape-like) ancestor.
I really don't get your source of total confusion here.
Evolution theory is extremely easy to understand and without confusion.
Surveillance_Egg_Unit
1.8 / 5 (5) Jul 05, 2018
-CONTINUED-
IF apes and ape-like animals share a common ancestor with humans as they claim, and it is claimed that humans are descended from H.Ergaster, H.Erectus, H.Floriensis, etc.. then it must be that apes and ape-like animals are also descended from H.Erectus, H.Ergaster, etc.
But then why did the apes not evolve as H. Sapiens was able to evolve if they ALL originated in East Africa as claimed by scientists? What was it that prevented the great apes from walking on the 2 legs consistently. Why didn't the apes lose their fur while living in a hot climate? Humans allegedly lost their fur after moving to cooler climates which makes no sense since fur would have protected them from the cold, wind and snow. Meanwhile, the apes kept their fur in a hot climate. That also makes no sense.
Surveillance_Egg_Unit
1.7 / 5 (6) Jul 05, 2018
if humans descended from such as H.Erectus, etc., then why do we share DNA with chimps, bonobos and gorillas?

Because chimps, bonobos, gorillas and H.Erectus all share a common (ape-like) ancestor.
I really don't get your source of total confusion here.
Evolution theory is extremely easy to understand and without confusion.

says humy

That is what I said. Read my post again. I am not denying evolution. I am saying that apes and humans allegedly share ancestry. Therefore, apes are also descended from H. Erectus and the others as much as humans allegedly are. But researchers haven't said that apes are descended from these Homo species, only humans are. But what came BEFORE these Homo species that are supposedly our mutual ancestors? What were they? What kind of animals were they? Were they mammals? Lizards? What?
humy
4.2 / 5 (5) Jul 05, 2018

IF apes and ape-like animals share a common ancestor with humans as they claim, and it is claimed that humans are descended from H.Ergaster, H.Erectus, H.Floriensis, etc.. then it must be that apes and ape-like animals are also descended from H.Erectus, H.Ergaster, etc.

NO. False inference. Just because WE are descended from H.Erectus doesn't logically entail that ALL apes are descended from H.Erectus.
As I explained to you before; chimps, bonobos, gorillas and H.Erectus all share a common (ape-like) ancestor.
I am saying that apes and humans allegedly share ancestry. Therefore, apes are also descended from H. Erectus

Again, false inference. You apparently don't understand the meaning of the word "therefore".
humy
4.3 / 5 (6) Jul 05, 2018
Surveillance_Egg_Unit

Nobody claims that, except for humans, modern primates are descendants of H.Erectus.
Saying we are descendants of H.Erectus doesn't imply all apes are and there is nothing in evolution theory that implies the contrary to this.
What part of H.Erectus and modern apes sharing a common ancestor do you not undersand?
FredJose
1 / 5 (7) Jul 05, 2018
More than 3 million years ago, our ancient human ancestors,

Once again - what was actually observed -

"This is the most complete foot of an ancient juvenile ever discovered." and
"...is part of a nearly complete {{{ 3.32-million-year-old }}} skeleton of a young female Australopithecus afarensis discovered in 2002"

-- and what is the interpretation of that observation???

What assumptions go into the determination of the age? You'd be very surprised at how that age is arrived at.
Who can confirm that this observed organism is really an ancestor of human beings?
Where is the observational support for such an assertion?

So far in real life, it is absolutely clear that a kind produces exactly that same kind and within that kind of organism is a limited amount of allowed variation - also known as speciation. There is no other observation of one kind of organism morphing into another even over thousands of generations. Darwinian evolutionary theory is a myth.

rrwillsj
3.7 / 5 (3) Jul 05, 2018
huny, you are debating creationist trolls. (devolved from ogres) They have a dogmatic ignorance of reality to fulminate.

One is based upon the fabulist racist hallucinogenic gibberish of alien-worshiping cults.

The other is a descendant of ancient illiterate slaves. Predecessors to the modern monotheistic religions. Based upon ancestral anthropophagic cult practices combined with poorly translated myths stolen from a succession of conquering masters.
.
humy
4 / 5 (4) Jul 05, 2018

What assumptions go into the determination of the age?

None other than known proven physics that, if wrong, nuclear power stations etc wouldn't work.
And assumptions like the data we see is real and we are not trapped in virtual reality etc; all reasonable assumptions than only loonies would insist are wrong.

https://en.wikipe...c_dating

Who can confirm that this observed organism is really an ancestor of human beings?

other scientists looking up the record of the same collected data to see and confirm what it shows to be true.
That is how science works.

humy
3.7 / 5 (3) Jul 05, 2018
...all reasonable assumptions than only loonies would insist are wrong....

misedit; that should be
"...all reasonable assumptions that only loonies would insist are wrong...."
TeeSquared
1 / 5 (2) Jul 05, 2018
That is how science works.


Scientific method: a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.

What part of the scientific method is used to determine:

1) the age of a pile of bones
2) whether the parents of the pile of bones was different that itself

jonesdave
3.7 / 5 (3) Jul 05, 2018
That is how science works.


Scientific method: a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.

What part of the scientific method is used to determine:

1) the age of a pile of bones
2) whether the parents of the pile of bones was different that itself



1) By dating various strata radiometrically. In this case, it was likely to be from volcanic tuff which, from memory, is dated by the K-Ar method.

2) By examining the juvenile foot architecture, and comparing it to those of adults from roughly the same time period, that have already been examined.

Quite simple, really.
TheGhostofOtto1923
1 / 5 (1) Jul 05, 2018
What assumptions go into the determination of the age? You'd be very surprised at how that age is arrived at.
Who can confirm that this observed organism is really an ancestor of human beings?
Where is the observational support for such an assertion?
Hey I got one... what makes fred think that asking a few dumb and obvious questions is a clever way of proving his point?

Fred is pretty dumb and obvious even for a religionist.
TeeSquared
1 / 5 (1) Jul 06, 2018
1) By dating various strata radiometrically. In this case, it was likely to be from volcanic tuff which, from memory, is dated by the K-Ar method.


The assumptions that are required in order to try to determine the age of a rock make that determination unreliable.

2) By examining the juvenile foot architecture, and comparing it to those of adults from roughly the same time period, that have already been examined.


Are you saying that the children's bones were different in structure than the adult bones??
humy
3.7 / 5 (3) Jul 06, 2018
1) By dating various strata radiometrically. In this case, it was likely to be from volcanic tuff which, from memory, is dated by the K-Ar method.


The assumptions that are required in order to try to determine the age of a rock make that determination unreliable.

Really? WHICH assumptions would they be then? Any examples? No? Well, its reliable then.
humy
3 / 5 (2) Jul 06, 2018
2) By examining the juvenile foot architecture, and comparing it to those of adults from roughly the same time period, that have already been examined.


Are you saying that the children's bones were different in structure than the adult bones??

Are you saying children's feet aren't smaller and of different proportions etc than adult's feet?
jonesdave
2.3 / 5 (3) Jul 06, 2018
The assumptions that are required in order to try to determine the age of a rock make that determination unreliable.


Wrong. Please tell us what these assumptions are. I think it is actually 40Ar/ 39Ar dating, rather than K/Ar, but the principle is the same. Are you saying the whole of our understanding of radiactivity is wrong? Or does it just not happen to fit in with whatever you want to believe?

Are you saying that the children's bones were different in structure than the adult bones??


Yes. Read the paper.

TeeSquared
1 / 5 (3) Jul 06, 2018
Wrong. Please tell us what these assumptions are.


* Conditions at Time Zero - whether the original rocks already contained daughter isotopes alongside their parent radioisotopes. Mt. St. Helen's crater formed and cooled in 1986, analyzed in 1996, contained so much argon-40 that it calculated to 350,000 years. Lava flows on Mt. Ngauruhoe, less than 50 years old, up to 3.5M years.

* No Contamination - The problems with contamination are already well-documented in the textbooks on radioactive dating. Because of such contamination, the less than 50 years old lava flows at Mt. Ngauruhoe, rubidium-strontium 133M years, samarium-neodymium 197M years, uranium-lead 3.908B years.

* Constant Decay Rate - Ongoing studies in the decay rates show that chemical environment and solar activity can have an effect. Comparing uranium decay to lead and the tiny amount of helium leaked in the same samples are evidence that decay rates are not as assumed.
SCVGoodToGo
3.7 / 5 (3) Jul 06, 2018
got citation for any of that?
barakn
4 / 5 (4) Jul 06, 2018
"As part of their efforts, YEC Dr. Steve Austin and his associates at the Institute for Creation 'Research' (ICR) collected a dacite sample from Mt. St. Helens, Washington State, USA, which probably erupted in 1986 AD. Austin et al. then ineffectively separated the sample into several mineral and glass 'fractions', submitted the dacite and its 'fractions' for potassium 40-argon 40 (K-Ar) dating, and subsequently used the bogus results to inappropriately attack the K-Ar method. ... With less advanced equipment, 'memory effects' can be a problem with very young samples (Dalrymple, 1969, p. 48). That is, very tiny amounts of argon contaminants from previous analyses may remain within the equipment, which precludes accurate dates for very young samples. For older samples, which contain more 40Ar, the contamination is diluted and has insignificant effects. " https://www.noans...e_kh.htm
TeeSquared
1 / 5 (2) Jul 06, 2018
As you can see, back and forth we can go with what we consider to be supporting evidences for our worldviews.

Bottom line ... is that way back when, something happened to start this material universe. All material things have to have a cause in order to become existent. The only thing that can cause a material thing to come into existence is something that is not part of the material thing being created.

So either the material universe:

- became existent because it appeared out of nothing. Logically and scientifically impossible.

- became existent because something immaterial caused it to exist.
rrwillsj
1 / 5 (1) Jul 11, 2018
Dear Stuporstitious, Now you just have that petty detail of proving HOW an immaterial supernatural entity manifested the material universe out of the immaterial of chaotic nothingness.

Then we just have to agree upon which incompetent deity is going to take the blame for bungling creation. Resulting in this meshugaas cosmos as a spectacular example of Stupid Design.

Cause fair's fair. You wouldn't want to inadvertently accuse the wrong incompetent deity? Would you?

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