Refuting Creationism - 'Lucy' Had a Cousin Species Who Lived Alongside Her

The Burtele Foot with its elements in the anatomical position.

Photo by Yohannes Haile-Selassie/ASU

New research by ASU paleoanthropologists: 2 ancient human ancestors were neighbors | ASU News.

According to new open-access research just published in Nature by a team led by Arizona State University palaeoanthropologist Yohannes Haile-Selassie, ‘Lucy’ (Australopithecus afarensis) was not the only hominin living on the Ethiopian Highlands 3.4 million years ago. This was part of the vast span of human evolutionary history that occurred long before creationists believe Earth was made as a small, flat world with a dome over it somewhere in the Middle East. Living alongside ‘Lucy’ was another species, now named Australopithecus deyiremeda.

However, A. deyiremeda differed from A. afarensis in several important ways — differences that reflect how two species can coexist in the same region by adapting to distinct ecological niches. A. deyiremeda, for instance, had an opposable big toe suited to climbing, indicating a more arboreal lifestyle than A. afarensis. Isotope analysis of A. deyiremeda’s teeth also shows that it had a different diet.

The first indication that another species might be present came in 2009 with the discovery of foot bones, announced publicly in 2012. In palaeontology, it is standard practice not to name a new species based on such fragmentary remains, especially when cranial bones are absent. Although teeth were also found in the same area, there was initially insufficient evidence to link them definitively to the foot bones.

Then, in 2015, the team had enough material to announce and name the new species, though they were still unable to demonstrate that the foot bones belonged to it. Now, ten years on, they believe they finally have sufficient fossil evidence to make that connection.

This news is unlikely to trouble creationists, who already have a ready supply of scientifically baseless excuses for dismissing ‘Lucy’: that it was forged; that scientists fabricated the evidence; that it was assembled from scattered bones found six miles apart; that ‘carbon dating’ was used (despite not being applicable at that age); or that radioactive decay rates have changed in the last 6,000–10,000 years, making 6,000 years only appear to be 3.4 million.

For those with the intellectual honesty and humility to form opinions based on evidence, however, the discovery offers a fascinating example of how multiple ancient hominins coexisted — and, in evolutionary terms, how two species sharing a common ancestor can diverge to occupy different ecological niches.

Where ‘Lucy’ Fits in the Hominin Family Tree.

The origin of our species | Natural History Museum

‘Lucy’ belongs to Australopithecus afarensis, a species that lived between about 3.9 and 3.0 million years ago across East Africa (Ethiopia, Kenya, Tanzania). In the hominin family tree, A. afarensis sits at a crucial, intermediate position: it is descended from earlier australopiths, but predates and potentially gave rise to later members of the genus Homo.

Key points about Lucy’s position:

1. Part of the Australopithecines
   A. afarensis is classified within the australopithecines — an early, diverse group of bipedal hominins. They are more derived than Ardipithecus but much earlier than Homo erectus and Homo sapiens.
2. Likely close to the last common ancestor of Homo
   Many researchers consider A. afarensis to be near the root of the Homo lineage. While not necessarily a direct ancestor, it is widely regarded as a species very close to (or part of) the population from which Homo evolved.
3. Exhibits key transitional features
   A. afarensis shows a mosaic of primitive and human-like traits:
   • Fully bipedal pelvis, femur and knee
   • Long arms and curved fingers suited to some climbing
   • Small brain, around 400–450 cc
   • Reduced canines and more human-like teeth
   This mix illustrates the gradual nature of human evolution: bipedalism was well established long before large brains evolved.
4. Coexisted with other hominins
   As this article discusses, A. afarensis was not alone. It overlapped with species such as A. deyiremeda, and possibly Kenyanthropus platyops and early A. africanus. Early hominin evolution was not a single-file progression but a branching bush with multiple contemporaneous species.
5. Probably ancestral to later Australopithecines
   Many later australopiths — A. africanus, the robust Paranthropus species — share clear similarities, suggesting that A. afarensis lies near the base of several later radiations.

The team’s research is summarised in an ASU news release by Nicole Pomerantz.

New research by ASU paleoanthropologists: 2 ancient human ancestors were neighbors

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Hominin foot fossil from Lucy’s time assigned to coexisting species — with help from teeth

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In 2009, scientists found eight bones from the foot of an ancient human ancestor within layers of million-year-old sediment in the Afar Rift in Ethiopia. The team, led by Arizona State University paleoanthropologist Yohannes Haile-Selassie, did not assign a species to the 3.4-million-year-old fossil — until now.

The fossil, called the Burtele Foot, was found at the Woranso-Mille paleontological site and was announced in a 2012 Nature article.

When we found the foot in 2009 and announced it in 2012, we knew that it was different from Lucy’s species, Australopithecus afarensis, which is widely known from that time. However, it is not common practice in our field to name a species based on postcranial elements — meaning elements below the neck — so we were hoping that we would find something above the neck in clear association with the foot. Crania, jaws and teeth are usually the elements used in species recognition.

Professor Johannes Haile-Selassie, Lead author
Institute of Human Origins
And School of Human Evolution and Social Change
Arizona State University
Tempe, AZ, USA.

When the Burtele Foot was announced, some teeth were already found from the same area, but the scientists were not convinced the teeth were from the same level of sediments. Then, in 2015, the team announced a new species, Australopithecus deyiremeda, from the same area — but were not able to conclusively include the foot into this species even though some of the specimens were found very close to the foot, Haile-Selassie says.

Now, after 10 years of going back into the field and continuing to find more fossils, Haile-Selassie said they have specimens that they can confidently associate with the Burtele Foot and with the species A. deyiremeda.

What's in a name — and a foot?

The assignment of the Burtele Foot to a species is just part of the story.

The site of Woranso-Mille is significant because it is the only site where scientists have clear evidence showing two related hominin species co-existed at the same time in the same area, explained Haile-Selassie.

The Burtele Foot, belonging to A. deyiremeda, is more primitive than the feet of Lucy’s species, A. afarensis. The Burtele Foot retained an opposable big toe, which is important for climbing, and the toes were longer and more flexible — also suitable for climbing.

But when A. deyiremeda walked on two legs, it most likely pushed off on its second digit rather than its big toe like we modern humans do today.

The presence of an abducted big toe in Ardipithecus ramidus was a big surprise because at 4.4 million years ago, there was still an early hominin ancestor which retained an opposable big toe, which was totally unexpected. Then 1 million years later, at 3.4 million years ago, we find the Burtele Foot, which is even more surprising. This is a time when we see species like A. afarensis whose members were fully bipedal with an adducted big toe. So what that means is that bipedality — walking on two legs — in these early human ancestors came in various forms. The whole idea of finding specimens like the Burtele Foot tells you that there were many ways of walking on two legs when on the ground; there was not just one way until later.

Professor Johannes Haile-Selassie.

What teeth tell us

To get insight into the diet of A. deyiremeda, Naomi Levin, a professor at the University of Michigan, sampled eight of the 25 teeth found at the Burtele areas for isotope analysis. The process involves cleaning the teeth, making sure to only sample the enamel and using very tiny tools like today’s dentists use.

I sample the tooth with a dental drill and a very tiny (< 1mm) bit. This equipment is the same kind that dentists use to work on your teeth. With this drill, I carefully remove small amounts of powder. I store that powder in a plastic vial and transport it back to our lab at the University of Michigan for isotopic analysis.

Professor Naomi E. Levin, co-author
Department of Earth and Environmental Sciences
University of Michigan
Ann Arbor, MI, USA.

The results were surprising.

While Lucy’s species was a mixed feeder, eating C3 resources (from trees and shrubs) and C4 plants (tropical grasses and sedges), A. deyiremeda was utilizing mostly C3 resources.

I was surprised that the carbon isotope signal was so clear and so similar to the carbon isotope data from the older hominins A. ramidus and Australopithecus anamensis. I thought the distinctions between the diet of A. deyiremeda and A. afarensis would be harder to identify, but the isotope data show clearly that A. deyiremeda wasn't accessing the same range of resources as A. afarensis, which is the earliest hominin shown to make use of C4 grass-based food resources.

Professor Naomi E. Levin.

Fragments of BRT-VP-2/135 before assembly. The specimen was found in 29 pieces of which 27 of them were recovered by sifting and picking the sifted dirt.

Image credit: Yohannes Haile-Selassie.

More clues from jaws

Along with the 25 teeth found at Burtele, scientists also found the jaw of a juvenile, which based on the anatomy of the teeth clearly belonged to A. deyiremeda.

This jaw had a full set of baby teeth already in position, but also had a lot of adult teeth developing deep down within the bony mandible, says Gary Schwartz, Institute of Human Origins research scientist and professor at the School of Human Evolution and Social Change.

Juvenile mandible digital reconstruction from microCT scans. Images in the left column show the jaw’s external details, while images in the right column show the external bone rendered partly transparent to see the adult teeth developing away deep within the bony mandible.

Reconstruction by Ragni and Schwartz/Courtesy of Nature.

For a juvenile hominin of this age, we were able to see clear traces of a disconnect in growth between the front teeth (incisors) and the back chewing teeth (molars), much like is seen in living apes and in other early australopiths, like Lucy’s species. I think the biggest surprise was despite our growing awareness of how diverse these early australopith (early hominin) species were — in their size, in their diet, in their locomotor repertoires and in their anatomy — these early australopiths seem to be remarkably similar in the manner in which they grew up.

Professor Gary T. Schwartz, Institute of Human Origins
And School of Human Evolution and Social Change
Arizona State University
Tempe, AZ, USA.

The team used state-of-the-art micro-CT scanning technology to look at all of the developing teeth because there is a close connection between both the pattern and pace of tooth development with a species’ overall growth biology. This allowed the scientists to estimate that this jaw belonged to a hominin that was around 4.5 years old when it died.

Knowing how these ancient ancestors moved and what they ate provides scientists with new knowledge about how species coexisted at the same time without one pushing the other to extinction.

All of our research to understand past ecosystems from millions of years ago is not just about curiosity or figuring out where we came from. It is our eagerness to learn about our present and the future as well. If we don’t understand our past, we can’t fully understand the present or our future. What happened in the past, we see it happening today,” he said. “In a lot of ways, the climate change that we see today has happened so many times during the times of Lucy and A. deyiremeda. What we learn from that time could actually help us mitigate some of the worst outcomes of climate change today.

Professor Johannes Haile-Selassie.

Haile-Selassie talks more about this project in an in-depth interview.

Publication:

Haile-Selassie, Y., Schwartz, G.T., Prang, T.C. et al.
New finds shed light on diet and locomotion in Australopithecus deyiremeda.
Nature (2025). https://doi.org/10.1038/s41586-025-09714-4

Abstract
The naming of Australopithecus deyiremeda¹ from Woranso-Mille (less than 3.59 to more than 3.33 million years) indicated the presence of a species contemporaneous with Australopithecus afarensis in the Ethiopian Afar Rift. A partial foot (BRT-VP-2/73)² and several isolated teeth from two Burtele (BRT) localities, however, were not identified to the species level. Recently recovered dentognathic specimens clarify not only the taxonomic affinity of the BRT hominin specimens but also shed light on the diet and locomotion of A. deyiremeda. Here we present a comparative description of these specimens and show that they are attributable to A. deyiremeda. We also find it parsimonious to attribute the BRT foot to this species based on the absence of other hominin species at BRT. The new material demonstrates that overall, A. deyiremeda was dentally and postcranially more primitive than A. afarensis, particularly in aspects of canine and premolar morphology, and in its retention of pedal grasping traits. Furthermore, the low and less variable distributions of its dental enamel δ¹³C values are similar to those from Ardipithecus ramidus and Australopithecus anamensis, indicating a reliance on C₃ foods. This suggests that A. deyiremeda had a dietary strategy similar to the earlier A. ramidus and A. anamensis. The BRT foot and its assignment to A. deyiremeda provides conclusive evidence that arboreality was a significant component of the positional behaviour of this australopith, further corroborating that some degree of arboreality persisted among Pliocene hominins^1,3,4,5,6,7.

Main
Hominin fossil discoveries in the past two decades suggest that multiple contemporaneous species existed in eastern Africa during the mid-Pliocene^1,2,8, but their validity, except for A. afarensis (a well-known Pliocene hominin species) has been questioned on various grounds including inadequate morphological distinction, small sample size or poor preservation^9,10,11. There appears to be a consensus, however, that the BRT foot (BRT-VP-2/73) from Woranso-Mille2, which was not assigned to a species at the time of its initial publication, is the strongest evidence for the presence of a non-A. afarensis species during the mid-Pliocene of eastern Africa^1,2,12,13,14. Some researchers have argued that the presence of human-like feet in some members of early Homo, variability in the foot morphology of australopiths and a foot with an opposable hallux in some of the earliest hominins such as A. ramidus all suggest diversity in pedal adaptations for bipedal locomotion¹⁵. More recent studies have further suggested that the BRT foot demonstrated the presence of variability in foot morphology and bipedal locomotor adaptation among species of Australopithecus^9,16,17, whereas others have hinted that the BRT foot belonged to a late-surviving species of Ardipithecus¹⁸ despite there being differences in the morphology of the first metatarsal and metatarsophalangeal joints¹⁹.

One of the reasons why the BRT foot and several isolated teeth from the BRT localities were not assigned to A. deyiremeda, despite their provenience from the same horizon as one of the paratypes of the species, was the lack of diagnosable dentognathic specimens that could be directly compared with the holotype and paratype specimens of the species². In the initial description of A. deyiremeda, it has been shown that some aspects of its maxillary and mandibular morphology were more derived than A. afarensis¹. However, its second and third molars, including other teeth from BRT, overlapped, both in size and shape, with A. afarensis and other Pliocene hominins. Further fieldwork at Woranso-Mille, particularly at the BRT localities, has now resulted in the recovery of additional, and more diagnostic, dentognathic specimens from the same horizon as and immediately below the BRT foot (Fig. 1). On the basis of the provenience (vertical and horizontal), it is more than likely that the dentognathic specimens from the BRT localities and the BRT foot belong to the same species: A. deyiremeda. The BRT hominins retain more primitive (A. anamensis-like) dental features than A. afarensis, and there is now evidence that like A. anamensis, they also had a C₃-dominated dietary adaptation.

Fig. 1: Location map, stratigraphy and provenience.

a, Map of Ethiopia showing the location of the Woranso-Mille site. GPTS, geomagnetic polarity time scale. b, Satellite image showing the location of the BRT area (white rectangle) relative to other nearby mid-Pliocene localities. KSD, Korsi Dora (3.6 Myr); LDD, Leado Dido’a (3.4 Myr); NFR, Nefuraytu (3.3 Myr). The black lines indicate observed fault lines. x-axis, latitude; y-axis, longitude. c, A closeup view of the BRT area showing the distribution of fossil hominins on the landscape. The squares represent the holotype and paratype specimens of A. deyiremeda. The circles represent previously and newly discovered specimens including BRT-VP-2/73 and BRT-VP-2/135 shown by the white arrows. The white line is the boundary between BRT-VP-1 and BRT-VP-2, and the black lines are the faults shown in panel b. d, Composite stratigraphical section of the BRT and WYT localities. The coloured vertical bars show the vertical extent of each locality in the section. The maximum age of the hominins from these localities is 3.55 ± 0.05 Myr based on a new ⁴⁰Ar/³⁹Ar age from K-feldspar dating of grains in a detrital sandstone (see Supplementary Information, Supplementary Fig. 1 and Supplementary Data 1 for details). The entire stratigraphical sequence exhibits normal paleomagnetic polarity, suggesting that the hominins are 3.596–3.330 Myr (chron C2An.3n). Panels b,c were modified from Google Earth (Data SIO, NOAA. U/S/ Navy, NGA, GEBCO; Image IBCAO; Image Landsat/Copernicus).

Haile-Selassie, Y., Schwartz, G.T., Prang, T.C. et al.
New finds shed light on diet and locomotion in Australopithecus deyiremeda.
Nature (2025). https://doi.org/10.1038/s41586-025-09714-4

Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Findings like this continue to show that human evolution was anything but a linear march toward a predetermined goal. Instead, the evidence reveals a branching, experiment-rich history in which multiple hominin species lived side by side, each adapting to particular environments in its own way. The existence of A. deyiremeda alongside A. afarensis adds another layer to this picture, showing that diversity — not simplicity — is the rule when we look far enough back into our evolutionary past.

For science, this discovery is simply the latest addition to a growing and coherent body of evidence. Each new fossil, each new analysis of diet, locomotion or environment, makes sense within the framework of evolution by natural selection. The pieces fit together: the anatomy, the geology, the dating, the ecology. Nothing needs to be bent or forced into place because the evidence dictates the conclusions, not the other way round.

For creationism, however, such findings are yet another awkward reminder that the real world stubbornly refuses to conform to a young Earth narrative. You cannot have two different hominin species occupying different ecological niches 3.4 million years ago if the entire planet is only a few thousand years old. Nor can you square the consistent pattern of branching evolutionary relationships with the idea of immutable “created kinds”. Every discovery of a new hominin species, especially one that coexisted with others, exposes the basic flaw in the creationist argument: it depends on denying the evidence rather than understanding it.

In the end, the contrast could not be clearer. Science continues to uncover a rich and complex human past, grounded in measurable, testable evidence. Creationism, by contrast, is left to recycle unfounded claims, conspiracy theories and attempts to discredit researchers. The discovery of Australopithecus deyiremeda does not merely illuminate our origins; it underscores yet again why evidence-based explanations succeed, and why creationist assertions fail.

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