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[CN]

5个阿法南方古猿的13个脚印已经发现。

A male is thought to have walked at least 30 metres with four females[CN]

一男携着四妻走了至少30米以上。

Calculations of height suggest he was at least 20cm taller than the females[CN]

身高的计算得出，他至少比其他女人高20cm。

The prints suggest Australopithecus afarensis may have had a gorilla-like social arrangement with a dominant male who mated with several women
[CN]

这个脚印表明，阿法南方古猿人可能有着与猩猩相同的社会架构 – 一夫多妻。

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[CN]

这些脚印是百万年前生活在这里的早期猿人群体留下的，在坦桑尼亚境内被发现。一男，携带4女，走了至少300米，经过火山灰，火山灰不久变成了石头。

The researchers believe that they belong to five members of Australopithecus afarensis – the prehuman species best known for the fossil skeleton, nicknamed 'Lucy'[CN]

研究者坚信这5人是阿法南方古猿人 – 以他们的化石骨架出名的类人猿，别号“露西”。

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[CN]

Dawid A. Iurino 2016年12月给出的这些说明，重新定义了坦桑尼亚366万年前的利特里古遗址，这一切都基于脚印的发现。

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[CN]

通过测量脚印的长宽，步幅和步态，调查者计算除了这5个类人猿的大致体重和身高。

The prints were found at Laetoli – a site which is famous for another set of smaller footprints left by Australopithecus afarensis individuals[CN]

脚印是在利特里发现的 - 这个古遗址还有另一组阿法南方古猿的小脚印，同样享誉世界。

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 13 footprints were discovered in Laetoli, Tanzania, by an international group of researchers, led by Sapienza University in Rome

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. 

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.

'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.

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.'

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.

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.

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.