Welcome to Learning English, a daily 30-minute program from the Voice of America.

I'm Katie Weaver.

And I'm Mario Ritter, Jr.

This program is designed for English learners, so we speak a little slower and we use

words and phrases especially written for people learning English.

Coming up on the show, Jill Roberts brings us the Health and Lifestyle Report.

She tells about a new study on the incidence of diabetes worldwide.

The researchers say more than 800 million adults have the disease, and they say more than half of people over 30 who have the disease are not receiving treatment for it.

We also hear from Brian Lynn. He reports on Microsoft's effort to expand its AI offerings with personal agents designed to take over different human processes.

And we close the show with our lesson of the day.

Andrew Smith and Jill Robbins teach us about how to express habitual past actions in English.

But first, I have a story on some ancient footprints found in Kenya and what they mean to the

paleontologists and other scientists studying them.

Scientists say ancient footprints left in wet dirt on a Kenyan lakeside suggests that two early human ancestors

were neighbors about 1.5 million years ago. 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.

Scientists already knew from earlier fossil finds that these two extinct lines of human

development, called Homo erectus and Peranthropis Boise, lived about the same time

in the Turkana basin. 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. Yet, with fossil footprints, there's an actual moment in time preserved,

...