Ileret (also spelled Illeret) is a village in

Marsabit County Marsabit County is a county in Kenya. Covering a surface area of 66,923.1 square kilometres. Marsabit is the second largest county in Kenya. Its capital is Marsabit and its largest town Moyale. According to the 2019 census, the county has a po ...

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

. It is located in Northern Kenya, on the eastern shore of

Lake Turkana Lake Turkana (), formerly known as Lake Rudolf, is a lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. B ...

, north of Sibiloi National Park and near the

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

n border. Numerous hominin fossils have been found near Ileret, including ''

Homo erectus ''Homo erectus'' (; meaning "upright man") is an extinct species of archaic human from the Pleistocene, with its earliest occurrence about 2 million years ago. Several human species, such as '' H. heidelbergensis'' and '' H. antecessor ...

'' footprints dating back to about 1.5 million years ago, making them the second oldest hominin footprints ever found after those at Laetoli, Tanzania.

Hominin fossils found near Ileret

Besides the ''Homo erectus'' footprints, numerous other fossils have been found near the Ileret site. In 2012–2013, a team of researchers from

Stony Brook University Stony Brook University (SBU), officially the State University of New York at Stony Brook, is a public research university in Stony Brook, New York. Along with the University at Buffalo, it is one of the State University of New York system' ...

found new hominin fossils near Ileret, in two sites within the Kolom Odiet area. The fossils were representative of three different individuals, composing of two partial skeletons – KNM-ER ( Kenya National Museum – East Rudolf) 64061 and KNM-ER 64062 – and an almost entirely completed

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, KNM-ER 64060. KNM-ER 64060 and KNM-ER 64061 date back to 2.02 to 2.03 Ma, and KNM-ER 64062 goes back 1.82 to 1.86 million years ago. The KNM-ER 64060 mandible is only missing the right

central incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

. The KNM-ER 64061 partial skeleton includes most of both humeral shafts, a partial right

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

and right

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the r ...

, and a right

shoulder blade The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either ...

. Its longer bones appeared to be slender, yet thick in its cross-sections. The KNM-ER 64062 skeleton possesses parts of a distal right humerus and

scaphoid The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid bone i ...

, and parts of a right foot with both primitive and derived features. These three individuals most likely represent members of early ''Homo'', the mandible being from ''

Homo habilis ''Homo habilis'' ("handy man") is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.31 million years ago to 1.65 million years ago (mya). Upon species description in 1964, ''H. habilis'' was highly ...

'' and the partial skeletons being from ''

''.

''Homo erectus'' footprints at Ileret

Fossilized footprints of ''Homo erectus'' were found in Ileret, Kenya. ''Science'' reported that there were multiple trails of footprints found at the Ileret site: “two trails of two prints each, one of seven prints and a number of isolated prints.” Citation error. See inline comment how to fix. These footprints reveal that these early hominins most likely traveled in groups—evidence which researchers see as a sign of social behavior.Citation error. See inline comment how to fix. Certain social behaviors distinguish humans from other primate species. Researchers attempt to find evidence of similar behaviors in the fossil or footprint records, however, it is difficult because this kind of fossil evidence is lacking. ''Homo erectus'' fossils were discovered in 1.5 million-year-old layers of

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

. These fossils supplied information about soft-tissue and foot structure. Unlike the fossils, the footprints provide researchers with information about early foot anatomy. Moreover, other ''Homo erectus'' fossils have been found in nearby areas and are the approximately the same age as the footprints found at Ileret.

''Homo erectus'' compared to other hominins

Differences have been found between these footprints and common apes. According to

Rutgers University Rutgers University (; RU), officially Rutgers, The State University of New Jersey, is a public land-grant research university consisting of four campuses in New Jersey. Chartered in 1766, Rutgers was originally called Queen's College, and was ...

, “the big toe is parallel to the other toes, unlike that of apes where it is separated in a grasping configuration useful in the trees.” The arch of the footprint is also human-like and the toes are much shorter than those of an ape. Short toes are a sign of “upright bipedal stance.” Additionally, relevant observations point to similarities between ''H. erectus'' and modern humans. The footprints reveal comparable body weights, strides and gaits. These early hominins are the first to have such similar body proportions to modern humans (''Homo sapiens''). Homo footprints

Evidence of bipedalism

Bipedalism Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...

is a characteristic of modern humans. Fossil evidence reveals that hominins walked on two feet as early as 6 to 7 million years ago. It can be difficult to reconstruct

gait Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. ...

evolution due to the inadequacy and scarcity of the fossil record. Often, fragments of bones are discovered and offer little information about hominins’ walking manners. Additionally, the hominin fossil record does not provide information concerning the social patterns of modern humans and other primates—patterns which drove evolution. The Ileret footprints provide significant evidence that ''Homo erectus'' was a bipedal hominin. The footprints provide evidence for a “modern human-like weight transfer” and support earlier discussions of ''

’'' arched foot.

Researchers

The footprints were discovered in 2007 by John W. Harris, BG Richmond, and David R. Braun.

References

External links

Human Timeline (Interactive)
– Smithsonian,

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7. ...

(August 2016). {{Archaeological sites in Kenya Populated places in Marsabit County Lake Turkana Archaeological sites in Kenya Pleistocene paleontological sites of Africa Prehistoric Africa Paleoanthropological sites Archaeological sites of Eastern Africa