Scientists say ancient footprints left in wet dirt on a Kenyan lakeside suggest that two early human ancestors were neighbors about 1.5 million years ago.
科学家表示，肯尼亚湖畔湿泥土中留下的古代脚印表明，大约 150 万年前，两个早期人类祖先是邻居。
Two separate species made the sets of footprints “within a matter of hours, or at most days,” said paleontologist Louise Leakey, a writer of the research published recently in the journal Science. Paleontologists study fossils to learn about the history of life on Earth.
最近发表在《科学》杂志上的这项研究的作者、古生物学家路易丝·利基 (Louise Leakey) 说，两个不同的物种“在几个小时内，或者最多几天内”就留下了这组脚印。古生物学家研究化石是为了了解地球上生命的历史。
Scientists already knew from earlier fossil finds that these two extinct lines of human development – called Homo erectus and Paranthropus boisei – lived about the same time in the Turkana Basin.
科学家们从早期的化石发现中已经知道，这两个已灭绝的人类进化谱系——直立人和博伊西傍人——大约同时生活在图尔卡纳盆地。
But dating fossils is not exact. “It’s plus or minus a few thousand years,” said paleontologist William Harcourt-Smith of Lehman College and the American Museum of Natural History in New York. He was not involved in the study
但化石年代测定并不准确。“这正负了几千年，”纽约雷曼学院和美国自然历史博物馆的古生物学家威廉·哈考特·史密斯说。他没有参与这项研究
Yet with fossil footprints, “there’s an actual moment in time preserved,” he said. “It’s an amazing discovery.”
然而，有了化石足迹，“就保存了一个真实的时间点，”他说。“这是一个惊人的发现。
” Researchers found the fossil footprints in 2021 in what is today Koobi Fora, Kenya, said Leaky, who is based at Stony Brook University in New York.
纽约石溪大学的 Leaky 表示，研究人员于 2021 年在今天的肯尼亚库比福拉发现了化石足迹。
Study co-writer Kevin Hatala is a paleoanthropologist at Chatham University in Pittsburgh, Pennsylvania. He said the two species likely knew of each other’s existence whether they left the prints at the same time or a day or two apart.
研究合著者凯文·哈塔拉是宾夕法尼亚州匹兹堡查塔姆大学的古人类学家。他说，这两个物种很可能知道彼此的存在，无论它们是同时留下的脚印还是相隔一两天留下的脚印。
“They probably saw each other, probably knew each other was there and probably influenced each other in some way,” Hatala said.
哈塔拉说：“他们可能见过对方，可能知道对方在那里，并且可能以某种方式互相影响。
” Scientists were able to tell the difference between the two species because of the shape of the footprints. The shape of each informed researchers about the structure of the foot and how it was being used at the time.
由于脚印的形状，科学家们能够区分这两个物种。每个脚的形状都让研究人员了解脚的结构以及当时的使用方式。
Homo erectus appeared to be walking similarly to how modern humans walk – striking the ground heel first, then moving weight over the ball of the foot and toes and pushing off again.
直立人的行走方式似乎与现代人的行走方式类似——脚跟先着地，然后将重量转移到脚掌和脚趾上，然后再次推出。
The other species, which was also walking upright, was moving “in a different way from anything else we’ve seen before, anywhere else,” said co-writer Erin Marie Williams-Hatala, a human development anatomist at Chatham.
另一种物种也是直立行走，其移动方式“与我们之前在其他地方见过的任何其他物种都不同”，查塔姆人类发育解剖学家、合著者艾琳·玛丽·威廉姆斯-哈塔拉（Erin Marie Williams-Hatala）说。
Among other details, the footprints suggest greater ability of movement in their big toe, compared to Homo erectus or modern humans, said Hatala.
哈塔拉说，除其他细节外，这些脚印表明，与直立人或现代人类相比，他们的大脚趾具有更强的运动能力。
Our common primate ancestors probably had hands and feet fit for grasping branches. But, over time, the feet of human ancestors developed to permit walking upright, researchers say.
我们共同的灵长类祖先可能有适合抓握树枝的手和脚。但研究人员表示，随着时间的推移，人类祖先的脚进化到可以直立行走。
The new study adds to a growing amount of research that suggests the change to walking on two feet did not happen at a single moment, in a single way.
越来越多的研究表明，双脚行走的改变并不是在某一时刻以单一方式发生的，这项新研究是对这一结果的补充。
Instead, there may have been a number of ways that early humans learned to walk, run and slide on prehistoric muddy hills.
相反，早期人类可能通过多种方式学会了在史前泥泞的山丘上行走、跑步和滑行。
“It turns out, there are different gait mechanics – different ways of being bipedal,” said Harcourt-Smith. “
事实证明，存在不同的步态机制——双足行走的不同方式，”哈考特-史密斯说。
