LD 350-1 is the earliest known specimen of the genus Homo, dating to 2.75–2.8 million years ago (mya), found in the Ledi-Geraru site in the Afar Region of Ethiopia.

However, the specimen's anatomy strongly diverges from australopithecines and more closely aligns with Homo: the mental foramina are not located on a depression, it has a symphyseal keel (a line of bone jutting out at the midline of the jaws), the jawbone maintains a more or less constant depth whereas it is deepest under the premolars in some Australopithecus, and there are several differences regarding the tooth crowns.

[3] The KNM-ER 5431 specimen (comprising left and right premolars and the first two molars) from Koobi Fora, Kenya, dating to 3–2.7 mya could represent the same species as LD 350-1.

In either case, the transition to sharper tools would have allowed different feeding strategies and the ability to process a wider range of foods than australopithecine technology permitted, which would have been advantageous in the changing climate of the time.

[3] Given the abundance of grazing animals the area was likely similar to modern day African open grasslands, such as the Serengeti or the Kalahari; but the presence of Deinotherium bozasi (a browser) may indicate gallery forests; and Hippopotamus afarensis, crocodiles and fish indicate river and lake systems.