Zeresenay Alemseged

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Zeresenay Alemseged
Zeresenay Alemseged.jpg
Born
Axum
Alma mater Addis Ababa University, University of Paris
Known forPaleoanthropology and the discovery of the Selam/Dikika Child Australopithcecus afarensis fossil
Scientific career
Fields Paleoanthropology, Anthropology
Institutions University of Chicago

Zeresenay "Zeray" Alemseged (born 4 June 1969) is an paleoanthropologist who is a faculty member at the University of Chicago. [1] In 2013, he was named a Fellow of the American Association for the Advancement of Science. [2] He was elected to the American Academy of Arts & Sciences in 2021. [3] In 2022, he was appointed to the Comité Scientifique International du Musée d’Anthropologie Préhistorique de Monaco [4] and the Pontifical Academy of Science. [5] Alemseged is best known for his discovery, on 10 December 2000, of Selam, also referred to as the "Dikika child" or “Lucy’s child”, the almost-complete fossilized remains of a 3.3 million-year-old child of the species Australopithecus afarensis . [6] The “world’s oldest child”, she is the most complete skeleton of a human ancestor discovered to date. Selam represents a milestone in understanding of human and pre-human evolution and contributes significantly to understanding of the biology and childhood of early species in the human lineage; [7] a subject about which we have very little information. Alemseged discovered Selam while working with the Dikika Research Project (DRP), a multi-national research project funded in part by the National Science Foundation, [8] which he both initiated in 1999 and leads. The DRP has thus far made many important paleoanthropological discoveries and returns to the field each year to conduct further important research. Alemseged's specific research centers on the discovery and interpretation of hominin fossil remains and their environments, with emphasis on fieldwork designed to acquire new data on early hominin skeletal biology, environmental context, and behavior.

Contents

Education and career

Alemseged began his professional career as a geologist. After graduating with a B.Sc. in Geology from Addis Ababa University in Ethiopia in 1990, he began working as a Junior Geologist in the National Museum of Ethiopia's Paleoanthropology Laboratory.

After obtaining a French language diploma in 1993, from the International Language School in Vichy, France, he began a M.Sc. program in the Institut des sciences de l'évolution at the University of Montpellier II in France. He completed this program in 1994 and earned a Ph.D. in paleoanthropology through the Laboratory of Paleontology at Pierre and Marie Curie University and the Muséum national d'histoire naturelle, Paris in 1998.

Alemseged then moved back to Ethiopia, and it was the next year, 1999, while working as a research associate at the National Museum of Ethiopia and the French Center for Ethiopian Studies in Addis Ababa, Ethiopia, that he formed the Dikika Research Project (DRP), the first Ethiopian-led paleoanthropological field research project, whose ongoing multi-national and multi-disciplinary mission is aimed at recovering data addressing Alemseged's primary research interests: hominin evolution and the ways by which that evolution was influenced by the paleoenvironment. Alemseged both leads the project and studies the recovered hominins and other primates.

From 2000 to 2003 Alemseged worked as a postdoctoral research associate at the Institute of Human Origins in the School of Human Evolution and Social Change at Arizona State University. It was at the beginning of his postdoctoral research that Alemseged made his most significant discovery of “Selam”. Only one small piece of Selam's skeleton was found in 2000; it would take an additional six years for her to be fully extracted and analyzed before preliminary results were published in Nature in 2006. In 2004 Alemseged moved back to Europe and became a senior researcher in the Department of Human Evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Alemseged stayed with the Max Planck Institute until 2008, at which point he became the Curator and Irvine Chair of Anthropology at the California Academy of Sciences in San Francisco.

In 2016, Alemseged joined the University of Chicago where he was later named the Donald N. Pritzker Professor. [9]

The Dikika Child "Selam"

On December 10, 2000, the Dikika Research Project (DRP), led by Dr. Alemseged, found the first piece of a major paleoanthropological discovery. The team, which was then composed of only Alemseged and three Ethiopian assistants, found the skull of a fossilized child that year and over the course of five successive field seasons between 2000 and 2005, after an intensive process of screening and excavation, the team recovered the partial skeleton of Selam: the earliest and most complete juvenile human ancestor ever found. [10] She is a member of the species Australopithecus afarensis, she was 3 years old when she died and she predated Lucy by 150,000 years.

The discovery's significance lay not only in Selam's antiquity, but also in her age at death. Although relatively complete infant skeletons have been recovered for more recent human species, not a single juvenile skeleton has been found for any of the species in the preceding millions of years. Most of these early finds consist of nothing more than a skull, a piece of jaw or some isolated teeth. In contrast to these relatively sparse finds, not only was the DRP team able to recover Selam's complete skull, but also a sandstone impression of her brain and even the hyoid bone. Due to the fragility of the hyoid, such a discovery in a species of Selam's antiquity is almost completely unprecedented. The team was able to recover a significant portion of Selam's bones below the neck as well, including most of the spinal column, the ribs, both collar bones and both shoulder blades. These bones are almost completely absent in the fossil record, except for fragmentary pieces from Lucy. Both knee caps and large portions of the thigh and shin bones from each leg were recovered, as well as an almost complete foot.

The bones show no indications of cuts or abrasions, nor do they show the type of damage associated with scavenging carnivores; this suggests that she was buried rapidly, perhaps by a flood, shortly after her death. It is also possible that it was this flood event which killed her. As the sediment pressed down on her through the years, Selam's bones became basically glued together in a highly compressed sandstone block. Usually paleoanthropologists struggle to reassemble fragmentary skeletal finds so as to place them back together, but Alemseged faced the exact opposite situation with Selam. He worked painstakingly to extricate her impacted skeleton, using dental tools and removing the soil from her ribs and twisted spinal column virtually grain by grain. The process took 6 years before it announced in 2006 and is still ongoing.

Selam's skull was CT scanned and it was this method that allowed her sex and age at death to be determined. Further analyses were able to establish the size of Selam's brain which, at approximately 330 cubic centimeters, would not have been very different from that of a 3-year-old chimpanzee. Whereas chimpanzees at this age have already formed over 90% of their brains, Selam had formed less than 90% of the adult brain size of her species when she died. This might point to a relatively slow brain growth in Australopithecus afarensis, similar to the brain growth pattern of modern humans, rather than that of chimps; this may point to a possible behavioral shift in Selam's species 3.5 million years ago and the emergence of the delayed pattern of brain development and maturity that we know of as human “childhood”.

The post-cranial skeleton also yielded several important lines of data regarding the locomotion (movement) and height of Australopithecus afarensis. The femur (thigh bone), tibia (shin bone), and foot indicate that Selam (and hence the species she represents) walked fully upright, even at 3 years old, while the shoulder bones are more similar to those of gorillas. Selam's fingers, as well as those of other members of Australopithecus afarensis, are long and curved. This suggests that while the species was an effective biped while on the ground, it retained the ability to climb, which would have been a beneficial adaptation for avoiding predators, especially at night and especially for the smaller or younger members of the species.

The rare presence of the hyoid bone also yielded some significant data pertaining to Selam's species. In this bone Selam is more similar to the African great apes than she is to modern humans. Along with a single Neanderthal example, Selam's hyoid is one of only two extinct hominin hyoids preserved in the fossil record and is the only example from a species of her antiquity. This bone is presumed to have played an important role in the development of human speech and its recovery gives us some clues towards understanding the nature and evolution of the human voicebox. This extraordinary ancient skeleton preserves a mosaic of features shared by both humans and the apes and clearly shows that both the anatomy and behavior of our ancestors was changing, slowly but progressively. In other words, evolution was in the making.

Research projects

The DRP
Alemseged's research interests lie in the discovery and analysis of new hominin and non-human primate fossils, with emphasis on the link between morphological changes over time and environmental transformations. To support these goals with new data, Alemseged initiated the Dikika Research Project (DRP) in 1999. This multidisciplinary project undertakes field research on sediments spanning in age from about 4.0 million to less than 500,000 years ago and addresses some of the major questions in paleoanthropology. The Pliocene site of Dikika, in Ethiopia, from which the project derives its name, is uniquely suited to answering these questions due to its strategic chronological placement. Sediments from Dikika are older than the oldest sediments from Hadar and are therefore closer to the time interval in which there is some fragmentary evidence for the diverse nature of the human lineage. Asbole on the other hand, another site studied by the DRP, represents the Middle Pleistocene, a time period that is poorly understood in the region.

Previous professional activities

The EAAPP
Alemseged was the Vice Chairperson and Chairperson of the East African Association of Paleontologists and Paleoanthropologists (the EAAPP), [11] before stepping down in 2022, which he co-founded along with Chairperson Dr. Emma Mbua. The EAAPP was officially launched in Kenya on July 18, 2005, and is the first organization of its kind in this region. Members of the EAAPP meet biannually to report on their research findings and address issues such as policy regarding research requirements, collections management, and fieldwork ethics. Though the research area is limited to East Africa, the researchers are a diverse group made up of scientists and students from Kenya, Ethiopia, Eritrea, Uganda, Tanzania, South Africa, Japan, Europe and the Americas.

California Academy of Sciences

The collaborative environment, in which original research and public outreach are given primacy, at the California Academy of Sciences (CAS) in San Francisco was suited to Alemseged's interests.

Alemseged and the DRP return to the Dikika field site every fall for anthropological work. The team's research during these field seasons has contributed significantly to the Academy's research on human origins and has added valuable data to the CAS Anthropological collection. Th multidisciplinary approach by the California Academy of Sciences to the biogeography of the region facilitates the study of the full spectrum of Africa's natural history and its vital role as the birthplace of mankind.

See also

Related Research Articles

<i>Ardipithecus</i> Extinct genus of hominins

Ardipithecus is a genus of an extinct hominine that lived during the Late Miocene and Early Pliocene epochs in the Afar Depression, Ethiopia. Originally described as one of the earliest ancestors of humans after they diverged from the chimpanzees, the relation of this genus to human ancestors and whether it is a hominin is now a matter of debate. Two fossil species are described in the literature: A. ramidus, which lived about 4.4 million years ago during the early Pliocene, and A. kadabba, dated to approximately 5.6 million years ago. Initial behavioral analysis indicated that Ardipithecus could be very similar to chimpanzees, however more recent analysis based on canine size and lack of canine sexual dimorphism indicates that Ardipithecus was characterised by reduced aggression, and that they more closely resemble bonobos.

<i>Homo habilis</i> Archaic human species from 2.1 to 1.5 mya

Homo habilis 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 contested, with many researchers recommending it be synonymised with Australopithecus africanus, the only other early hominin known at the time, but H. habilis received more recognition as time went on and more relevant discoveries were made. By the 1980s, H. habilis was proposed to have been a human ancestor, directly evolving into Homo erectus which directly led to modern humans. This viewpoint is now debated. Several specimens with insecure species identification were assigned to H. habilis, leading to arguments for splitting, namely into "H. rudolfensis" and "H. gautengensis" of which only the former has received wide support.

<i>Australopithecus</i> Genus of hominin ancestral to modern humans

Australopithecus is a genus of early hominins that existed in Africa during the Pliocene and Early Pleistocene. The genera Homo, Paranthropus, and Kenyanthropus evolved from some Australopithecus species. Australopithecus is a member of the subtribe Australopithecina, which sometimes also includes Ardipithecus, though the term "australopithecine" is sometimes used to refer only to members of Australopithecus. Species include A. garhi, A. africanus, A. sediba, A. afarensis, A. anamensis, A. bahrelghazali and A. deyiremeda. Debate exists as to whether some Australopithecus species should be reclassified into new genera, or if Paranthropus and Kenyanthropus are synonymous with Australopithecus, in part because of the taxonomic inconsistency.

<span class="mw-page-title-main">Donald Johanson</span> American paleoanthropologist

Donald Carl Johanson is an American paleoanthropologist. He is known for discovering, with Yves Coppens and Maurice Taieb, the fossil of a female hominin australopithecine known as "Lucy" in the Afar Triangle region of Hadar, Ethiopia.

<i>Australopithecus afarensis</i> Extinct hominid from the Pliocene of East Africa

Australopithecus afarensis is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa. The first fossils were discovered in the 1930s, but major fossil finds would not take place until the 1970s. From 1972 to 1977, the International Afar Research Expedition—led by anthropologists Maurice Taieb, Donald Johanson and Yves Coppens—unearthed several hundreds of hominin specimens in Hadar, Ethiopia, the most significant being the exceedingly well-preserved skeleton AL 288-1 ("Lucy") and the site AL 333. Beginning in 1974, Mary Leakey led an expedition into Laetoli, Tanzania, and notably recovered fossil trackways. In 1978, the species was first described, but this was followed by arguments for splitting the wealth of specimens into different species given the wide range of variation which had been attributed to sexual dimorphism. A. afarensis probably descended from A. anamensis and is hypothesised to have given rise to Homo, though the latter is debated.

Paleoanthropology or paleo-anthropology is a branch of paleontology and anthropology which seeks to understand the early development of anatomically modern humans, a process known as hominization, through the reconstruction of evolutionary kinship lines within the family Hominidae, working from biological evidence and cultural evidence.

<span class="mw-page-title-main">Laetoli</span> National Historic Site of Tanzania

Laetoli is a pre-historic site located in Enduleni ward of Ngorongoro District in Arusha Region, Tanzania. The site is dated to the Plio-Pleistocene and famous for its Hominina footprints, preserved in volcanic ash. The site of the Laetoli footprints is located 45 km south of Olduvai gorge. The location and tracks were discovered by archaeologist Mary Leakey and her team in 1976, and were excavated by 1978. Based on analysis of the footfall impressions "The Laetoli Footprints" provided convincing evidence for the theory of bipedalism in Pliocene Hominina and received significant recognition by scientists and the public. Since 1998, paleontological expeditions have continued under the leadership of Amandus Kwekason of the National Museum of Tanzania and Terry Harrison of New York University, leading to the recovery of more than a dozen new Hominina finds, as well as a comprehensive reconstruction of the paleoecology. The site is a registered National Historic Sites of Tanzania.

Hadar or Hadar Formation is a paleontological fossil site located in Mille district, Administrative Zone 1 of the Afar Region, Ethiopia, 15 km upstream (west) of the A1 road's bridge across the Awash River.

<i>Australopithecus africanus</i> Extinct hominid from South Africa

Australopithecus africanus is an extinct species of australopithecine which lived between about 3.3 and 2.1 million years ago in the Late Pliocene to Early Pleistocene of South Africa. The species has been recovered from Taung, Sterkfontein, Makapansgat, and Gladysvale. The first specimen, the Taung child, was described by anatomist Raymond Dart in 1924, and was the first early hominin found. However, its closer relations to humans than to other apes would not become widely accepted until the middle of the century because most had believed humans evolved outside of Africa. It is unclear how A. africanus relates to other hominins, being variously placed as ancestral to Homo and Paranthropus, to just Paranthropus, or to just P. robustus. The specimen "Little Foot" is the most completely preserved early hominin, with 90% of the skeleton intact, and the oldest South African australopith. However, it is controversially suggested that it and similar specimens be split off into "A. prometheus".

<i>Australopithecus anamensis</i> Extinct hominin from Pliocene east Africa

Australopithecus anamensis is a hominin species that lived approximately between 4.2 and 3.8 million years ago and is the oldest known Australopithecus species, living during the Plio-Pleistocene era.

<i>Australopithecus garhi</i> Extinct hominid from the Afar Region of Ethiopia 2.6–2.5 million years ago

Australopithecus garhi is a species of australopithecine from the Bouri Formation in the Afar Region of Ethiopia 2.6–2.5 million years ago (mya) during the Early Pleistocene. The first remains were described in 1999 based on several skeletal elements uncovered in the three years preceding. A. garhi was originally considered to have been a direct ancestor to Homo and the human line, but is now thought to have been an offshoot. Like other australopithecines, A. garhi had a brain volume of 450 cc (27 cu in); a jaw which jutted out (prognathism); relatively large molars and premolars; adaptations for both walking on two legs (bipedalism) and grasping while climbing (arboreality); and it is possible that, though unclear if, males were larger than females. One individual, presumed female based on size, may have been 140 cm tall.

<span class="mw-page-title-main">Afar Region</span> Regional state in northeastern Ethiopia

The Afar Region, formerly known as Region 2, is a regional state in northeastern Ethiopia and the homeland of the Afar people. Its capital is the planned city of Semera, which lies on the paved Awash–Assab highway. It’s bordered by Eritrea to the north and Djibouti to the northeast; it also shares regional borders with the Tigray, Amhara, Oromo and Somali regions.

<span class="mw-page-title-main">Middle Awash</span> UNESCO World Heritage Site in Ethiopia

The Middle Awash is a paleoanthropological research area in the northwest corner of Gabi Rasu in the Afar Region along the Awash River in Ethiopia's Afar Depression. It is a unique natural laboratory for the study of human origins and evolution and a number of fossils of the earliest hominins, particularly of the Australopithecines, as well as some of the oldest known Olduwan stone artifacts, have been found at the site—all of late Miocene, the Pliocene, and the very early Pleistocene times, that is, about 5.6 million years ago (mya) to 2.5 mya. It is broadly thought that the divergence of the lines of the earliest humans (hominins) and of chimpanzees (hominids) was completed near the beginning of that time range, or sometime between seven and five mya. However, the larger community of scientists provide several estimates for periods of divergence that imply a greater range for this event, see CHLCA: human-chimpanzee split.

Lucy (<i>Australopithecus</i>) 3.2-million-year-old fossilized hominid

AL 288-1, commonly known as Lucy or Dink’inesh, is a collection of several hundred pieces of fossilized bone comprising 40 percent of the skeleton of a female of the hominin species Australopithecus afarensis. It was discovered in 1974 in Ethiopia, at Hadar, a site in the Awash Valley of the Afar Triangle, by Donald Johanson, a paleoanthropologist of the Cleveland Museum of Natural History.

<span class="mw-page-title-main">Little Foot</span> Hominin fossil

"Little Foot" is the nickname given to a nearly complete Australopithecus fossil skeleton found in 1994–1998 in the cave system of Sterkfontein, South Africa.

Selam (<i>Australopithecus</i>) Hominin fossil

Selam (DIK-1/1) is the fossilized skull and other skeletal remains of a three-year-old Australopithecus afarensis female hominin, whose bones were first found in Dikika, Ethiopia in 2000 and recovered over the following years. Although she has often been nicknamed Lucy's baby, the specimen has been dated at 3.3 million years ago, approximately 120,000 years older than "Lucy".

The Dikika is an area of the Afar Region of Ethiopia. A hominin fossil named Selam, a specimen of the Australopithecus afarensis species, was found in this area. Papers also propose the earliest evidence of stone tool use at this site in the form of cut marks on animal bone. However there has been argument about this proposal. Dikika is located in Mille woreda.

AL 333, commonly referred to as the "First Family", is a collection of prehistoric hominid teeth and bones. Discovered in 1975 by Donald Johanson's team in Hadar, Ethiopia, the "First Family" is estimated to be about 3.2 million years old, and consists of the remains of at least thirteen individuals of different ages. They are generally thought to be members of the species Australopithecus afarensis. There are multiple theories about the hominids' cause of death and some debate over their species and sexual dimorphism.

<i>Australopithecus sediba</i> Two-million-year-old hominin from the Cradle of Humankind

Australopithecus sediba is an extinct species of australopithecine recovered from Malapa Cave, Cradle of Humankind, South Africa. It is known from a partial juvenile skeleton, the holotype MH1, and a partial adult female skeleton, the paratype MH2. They date to about 1.98 million years ago in the Early Pleistocene, and coexisted with Paranthropus robustus and Homo ergaster / Homo erectus. Malapa is interpreted as having been a natural death trap, the base of a long vertical shaft which creatures could accidentally fall into. A. sediba was initially described as being a potential human ancestor, and perhaps the progenitor of Homo, but this is contested and it could also represent a late-surviving population or sister species of A. africanus which had earlier inhabited the area.

<span class="mw-page-title-main">Lomekwi</span> Kenyan archaeological site dated to 3.3 million years ago

Lomekwi is the name of an archaeological site in Kenya where ancient stone tools have been discovered dating back approximately 3.3 million years ago making them the oldest tools ever found.

References

  1. ↑ "Alemseged Lab – Alemseged Lab | University of Chicago". alemsegedlab.uchicago.edu. Retrieved 2023-04-05.
  2. ↑ "AAAS Council Elects 388 New AAAS Fellows | American Association for the Advancement of Science (AAAS)". www.aaas.org. Retrieved 2023-04-11.
  3. ↑ "Zeresenay Alemseged". American Academy of Arts & Sciences. Retrieved 2023-04-11.
  4. ↑ "Ordonnance Souveraine n° 9.086 du 11 février 2022 portant nomination des membres du Comité Scientifique International du Musée d'Anthropologie Préh... / Journal 8578 / Année 2022 / Journaux / Accueil - Journal de Monaco". journaldemonaco.gouv.mc. Retrieved 2023-04-11.
  5. ↑ "Zeresenay Alemseged". www.pas.va. Retrieved 2023-04-11.
  6. ↑ "DIK-1-1 (Selam)". www.talkorigins.org. Retrieved 2016-04-12.
  7. ↑ Gunz, Philipp; Neubauer, Simon; Falk, Dean; Tafforeau, Paul; Le Cabec, Adeline; Smith, Tanya M.; Kimbel, William H.; Spoor, Fred; Alemseged, Zeresenay (2020-04-03). "Australopithecus afarensis endocasts suggest ape-like brain organization and prolonged brain growth". Science Advances. 6 (14): eaaz4729. doi:10.1126/sciadv.aaz4729. ISSN   2375-2548. PMC   7112758 . PMID   32270044.
  8. ↑ "NSF Award Search: Award # 0914687 - Collaborative Research: Paleontological Field Research at Dikika, Ethiopia". www.nsf.gov. Retrieved 2023-04-11.
  9. ↑ "Faculty members receive named, distinguished service professorships | University of Chicago News". news.uchicago.edu. Retrieved 2023-04-05.
  10. ↑ Alemseged, Zeresenay; Spoor, Fred; Kimbel, William H.; Bobe, René; Geraads, Denis; Reed, Denné; Wynn, Jonathan G. (September 2006). "A juvenile early hominin skeleton from Dikika, Ethiopia". Nature. 443 (7109): 296–301. doi:10.1038/nature05047. ISSN   1476-4687.
  11. ↑ "EAAPP". EAAPP. Retrieved 2023-04-14.
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