The 3.6 million-year-old footprints that reveal how our ancient male ancestors had more than one mate at a time
- 13 footprints belonging to five Australopithecus afarensis were found
- A male is thought to have walked at least 30 metres with four females
- Calculations of height suggest he was at least 20cm taller than the females
- The prints suggest Australopithecus afarensis may have had a gorilla-like social arrangement with a dominant male who mated with several women
Footprints belonging to a group of early humans who lived 3.6 million years ago have been uncovered in Tanzania.
The
early impressions were made when five of our ancient relatives - most
likely Australopithecus afarensis - walked across wet volcanic ash.
Researchers
say the footprints suggest that members of Australopithecus afarensis
may have had a gorilla-like social arrangement of one dominant male
mating with several females.
Footprints belonging to a group of
early humans who lived millions of years ago have been uncovered in
Tanzania. A man, accompanied by four women was thought to have walked at
least 30 metres over the volcanic ash that later hardened into rock
AUSTRALOPITHECUS AFARENSIS
Australopithecus
afarensis is one of the longest-lived and best-known early human
species, who lived 3.85 to 2.95 million years ago in Eastern Africa.
The species survived for more than 900,000 years, which is over four times as long as our own species has been around.
Similar to chimpanzees, Au. afarensis children grew rapidly after birth and reached adulthood earlier than modern humans.
Au.
afarensis had both ape and human characteristics, with apelike face
proportions and long, strong arms with curved fingers adapted for
climbing trees.
They also had small canine teeth like all other early humans, and a body that stood on two legs and regularly walked upright.
The
13 footprints were discovered in Laetoli, Tanzania, by an international
group of researchers, led by Sapienza University in Rome.
The
researchers believe that they belong to five members of
Australopithecus afarensis – the prehuman species best known for the
fossil skeleton, nicknamed 'Lucy.'
A
man, accompanied by four women was thought to have walked at least 30
metres over the volcanic ash that later hardened into rock.
Professor
Giorgio Manzi, lead author of the study, said: 'This novel evidence,
taken as a whole with the previous findings, portrays several early
hominins moving as a group through the landscape following a volcanic
eruption and subsequent rainfall. But there is more.
'The
footprints of one of the new individuals are astonishingly larger than
anyone else's in the group, suggesting that he was a large male member
of the species.
The researchers believe that they
belong to five members of Australopithecus afarensis – the prehuman
species best known for the fossil skeleton, nicknamed 'Lucy'
'In fact, the 165cm stature indicated by his footprints makes him the largest Australopithecus specimen identified to date.'
The findings differ from previous studies that have suggested that Australopithecus afarensis males only had one sexual partner.
A study in
2003 by researchers from Penn State University performed extensive
simulations using modern humans, chimpanzees, and gorillas to understand
the sex lives of Australopithecus afarensis individuals.
In
their paper, the researchers, led by Dr Philip Reno, wrote that 'the
reproductive strategy of A afarensis was principally monogamy.'
The
prints were found at Laetoli – a site which is famous for another set
of smaller footprints left by Australopithecus afarensis individuals.
In the 1970s, those prints made headlines as the earliest clear evidence of upright walking by our ancestors.
This illustration provided by Dawid A.
Iurino in December 2016 shows a reconstruction of the northern Tanzanian
Laetoli site 3.66 million years ago, where the footprints were found
ESTIMATING HEIGHT FROM FOOTPRINTS
Measurements
of the length and width of the footprints, stride length and the angle
of the gait allowed the researchers to calculate rough weights and
heights for the five.
The
male came in at the heaviest and tallest, weighing 48.1kg (100 pounds)
and measuring about 5 foot 5 (165 centimetres), while the lightest only
weighed 28.5kg.
If
these measurements are correct, this would mean the male loomed more
than 20 centimetres (eight inches) above his fellow walkers.
The newly found prints are only 150 metres away.
Measurements
of the length and width of the footprints, stride length and the angle
of the gait allowed the researchers to calculate rough weights and
heights for the five.
The
male came in at the heaviest and tallest, weighing 48.1kg (100lbs) and
measuring about 5 foot 5 (165cm), while the lightest only weighed
28.5kg.
If
these measurements are correct, this would mean the male loomed more
than 20 centimetres (eight inches) above his fellow walkers.
Dr
Marco Cherin, who also worked on the study, said: 'A tentative
conclusion is that the group consisted of one male, two or three
females, and one or two juveniles, which leads us to believe that the
male - and therefore other males in the species - had more than one
female mate.'
Measurements of the length and width
of the footprints, stride length and the angle of the gait allowed the
researchers to calculate rough weights and heights for the five
The
large male-female disparity suggests that Australopithecus afarensis
may have had a gorilla-like social arrangement of one dominant male,
with a group of females and their offspring.
But not everyone is convinced by the researchers' analysis of the height.
Dr
William Jungers, a research associate at the Association Vahatra in
Madagascar who wrote a commentary on the study, says the estimate is
suspect.
The prints were found at Laetoli – a
site which is famous for another set of smaller footprints left by
Australopithecus afarensis individuals
In his commentary,
Dr Jungers wrote: 'It is important to note that foot length has only
been roughly estimated for this ancient species, and that the height
estimates would change if a different foot length-to-stature ratio was
used.'
In
November, researchers analysed the fossilised arm bones of Lucy, an
early hominin from the Australopithecus afarensis species, and suggested
that she was a tree climber.
Scans of Lucy's arm bones revealed her upper limbs were somewhere between a modern human and a chimpanzee.
In
November, researchers analysed the fossilised arm bones of Lucy, an
early hominin from the Australopithecus afarensis species, and suggested
that she was a tree climber
The
evidence gleaned from the scans proves she spent time climbing and used
her arms to pull herself up, potentially ending the long-running debate
among palaeontologists.
It also expands on evidence from earlier this year which claimed that Lucy may have died from a fall, most likely from a tree.
Taken
together, the evidence suggests that Australopithecus afarensis may
have been spent time on the ground, returning to the safety of the trees
for food and to sleep, to avoid predators.
The 13 footprints were discovered in
Laetoli, Tanzania, by an international group of researchers, led by
Sapienza University in Rome
No comments:
Post a Comment