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In fact, the footprints indicate these two species were walking along the lakeshore within hours or days of each other, according to a study published this week in Science that Feibel co-authored.

One day 1.5 million years ago, two or three individuals of our genus Homo walked along a muddy lakeshore.

The adjacent, more jagged lakeshore cliffs generate weaker and less distinct echoes, while the more or less contemporary dwelling sites on the sandy shores of the same water bodies have no audible echoes at all.

Yet the National Park Service maintains and protects hundreds of parks, national lakeshores and seashores, recreation areas, walking trails and more, all for you to take in and enjoy.

Spears and a double-pointed throwing stick were found lying between animal bones about ten meters below the surface in deposits at a former lakeshore.