This year brought many revelations about our ancient human relatives

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This is an excerpt from Our Human Story, a newsletter about the revolution in archaeology. Sign up to receive it in your inbox every month.

If we try to summarize all the new fossils, methods, and ideas emerging from the study of human evolution in 2025, we might still be here in 2027. This year has been packed with developments, and I doubt it’s feasible for one individual to digest everything without isolating themselves from other distractions. This is particularly true in human evolution, which is a decentralized field. Unlike particle physicists, who often unite in teams for large-scale experiments, paleoanthropologists scatter in diverse directions.

There are two ways this year-long endeavor can falter. One risk is getting overwhelmed by an insurmountable amount of research, rendering it indecipherable. The other is simplifying the information to the point where it becomes incorrect.

With that in mind, here are three key points I want to clarify as we head into 2025. First, there have been remarkable discoveries about the Denisovans, reshaping our understanding of this mysterious group and challenging some of our previous assumptions. Second, we’ve seen a variety of new discoveries and ideas regarding how our distant ancestors created and utilized tools. Finally, we must consider the broader picture: how and why our species diverged so significantly from other primates.

The Denisovan Flood

Hebei Geography University

This year marks 15 years since we first learned about the Denisovans, an ancient group of humans that inhabited East Asia tens of thousands of years ago. My fascination with them has persisted, and this year, I was excited to witness a surge of discoveries that broadened our knowledge of their habitats and identities.

Denisovans were initially identified primarily through molecular evidence. The first fossil discovered was a small finger bone from Denisova Cave in Siberia, which defied identification based solely on its morphology, but DNA was collected in 2010. Genetic analyses revealed that Denisovans were closely related to Neanderthals, who lived in Europe and Asia, and that they interbred with modern humans. Currently, populations in Southeast Asia, particularly Papua New Guinea and the Philippines, possess the highest concentration of Denisovan DNA.

Since then, researchers have been on the hunt for additional Denisovan remains, though this endeavor has progressed slowly. Until 2019, the second identified example was a jawbone excavated from Baisiya Karst Cave in Xianghe, located on the Tibetan Plateau. Over the next five years, several more fossils were tentatively attributed to Denisovans, notable for their large size and pronounced teeth compared to modern humans.

Then came 2025, which brought numerous exciting findings. In April, Denisovans were confirmed in Taiwan, when a jawbone dredged from the Penghu Strait in 2008 was finally identified using preserved proteins. This discovery significantly extends the known range of Denisovans to the southeast, aligning with where their genetic markers remain today.

In June, the first Denisovan facial features emerged. A skull discovered in Harbin, northern China, was described in 2021 and designated as a new species, named Homolonghi. Initially presumed to belong to Denisovans due to its large size, proteins extracted by Qiaomei Fu and her team from the bone and mitochondrial DNA from dental plaque confirmed its Denisovan origins.

So far, these findings align well with genetic evidence indicating that Denisovans roamed extensively across Asia. They also contribute to a coherent image of Denisovans as a larger species.

However, two additional discoveries in 2025 were surprising. In September, a crushed skull thought to belong to an early Denisovan was reconstructed in Unzen, China, dating back approximately 1 million years. This finding suggests that Denisovans existed as a distinct group much earlier than previously believed, indicating that their common ancestor with Neanderthals, known as Ancestor X, must have lived over a million years ago. If confirmed, it implies a longer evolutionary history for all three groups than previously thought.

Just a month ago, geneticists released a second high-quality Denisovan genome extracted from a 200,000-year-old tooth found in Denisova Cave. Notably, this genome is distinctly different from the first genome described recently, as well as from modern Denisovan DNA.

This indicates the existence of at least three groups of Denisovans: early ones, later ones, and those that hybridized with modern humans—this latter group remains a total archaeological enigma.

As our understanding of Denisovans deepens, their history appears much longer and more diverse than initially assumed. In particular, Denisovan populations that interbred with modern humans remain elusive.

For the past 15 years, Denisovans have captivated my interest. Despite their widespread presence across continents for hundreds of thousands of years, only a handful of remains have been documented.

Fortunately, I have a penchant for mysteries. Because this puzzle won’t be solved anytime soon.

Tool Manufacturing

TW Plummer, JS Oliver, EM Finestone, Houma Peninsula Paleoanthropology Project

Creating and using tools is one of humanity’s most critical functions. This ability isn’t unique to our species, as many other animals also use and even make tools. Primatologist Jane Goodall, who passed away this year, famously demonstrated that chimpanzees can manufacture tools. However, humans have significantly elevated this skill, producing a more diverse array of tools that are often more complex and essential to our survival than those of any other animal.

As we delve deeper into the fossil record, we’re discovering that the practice of tool-making dates back further than previously thought. In March, I reported on excavations in Tanzania revealing that an unidentified ancient human was consistently creating bone tools 1.5 million years ago, well over a million years before bone tools were believed to become commonplace. Similarly, while it was previously thought that humans began crafting artifacts from ivory 50,000 years ago, this year, a 400,000-year-old flake from a mammoth tusk was discovered in Ukraine.

Even older stone tools have surfaced, likely due in part to their greater preservation potential. Crude tools have been identified from 3.3 million years ago at Lomekwi, Kenya. Last month in Our Human Story, I mentioned excavations in another part of Kenya demonstrating that ancient humans consistently produced a specific type of Oldowan tools between 2.75 million and 2.44 million years ago, indicating that tool-making was already a habitual practice.

Often, tools are found without associated bones, making it challenging to determine their makers’ identities. It’s tempting to assume that most tools belong to our genus, Homo, or perhaps to Australopithecus, our more distant ancestors. However, increasing evidence suggests that Paranthropus—a hominin with a small brain and large teeth, which thrived in Africa for hundreds of thousands of years—could also have made tools, at least simple ones like the Oldowans.

Two years ago, Oldowan tools were discovered alongside Paranthropus teeth in Kenya—admittedly not definitive evidence, but strongly suggestive. This year, a fossil of Paranthropus revealed that its hand exhibited a combination of gorilla-like strength and impressive dexterity, indicating capable precision gripping essential for tool-making.

How did these ancients conceive of their tools? One possibility, suggested by Metin Eren and others this year, is that they didn’t consciously create them. Instead, tool-like stones form naturally under various conditions, such as frost cracking rocks or elephants trampling them. Early humans may have utilized these “natural stones,” knowledge of which eventually led to their replication.

As humans continued to develop increasingly complex tools, the cognitive demands of creating them likely escalated, potentially facilitating the emergence of language as we needed to communicate how to make and use these advanced tools. This year’s research explored aspects like the difficulty of learning various skills, whether close observation is necessary, or if mere exposure suffices. The findings suggest two significant changes in cultural transmission that may correlate with technological advancements.

Like most aspects of evolution, tool-making appears to have gradually evolved from our primate predecessors, reshaping our cognitive capabilities in the process.

Big Picture

Alexandra Morton Hayward

Now let’s address the age-old question of how and why humans evolved so distinctly, and which traits truly set us apart. This topic is always challenging to navigate for three main reasons.

First, human uniqueness is multifaceted and often contradictory. Social scientist Jonathan R. Goodman suggested in July that evolution has forged humans to embody both “Machiavellian” traits—planning and betraying one another—and “natural socialist” instincts driven by strong social norms against murder and theft. Claims that humans are inherently generous or instinctively cruel tend to oversimplify the matter excessively.

Second, our perceptions of what makes us unique are shaped by the societies in which we exist. For instance, many cultures remain predominantly male-focused, leading our historical narratives to center around men. While the feminist movement is working to amend this imbalance, progress remains slow. Laura Spinney’s article on prehistoric women suggested that “throughout prehistory, women were rulers, warriors, hunters, and shamans,” a viewpoint made viable only through dedicated research.

Third, reconstructing the thought processes of ancient people as they adopted certain behaviors is inherently difficult, if not impossible. Why did early humans bury their dead and enact funerary rituals? How were dogs and other animals domesticated? What choices shaped ancient humans’ paths toward change?

Still, I want to spotlight two intriguing ideas surrounding the evolution of the human brain and intelligence. One concerns the role of placental hormones that developing babies are exposed to in the womb. Preliminary evidence suggests these hormones may contribute to brain growth, equipping us with the neural capacity to navigate our unusually complex social environments.

Another compelling possibility proposes that the genetic changes associated with our increased intelligence may have also led to vulnerabilities to mental illness. In October, Christa Leste-Laser reported that genetic mutations linked to intelligence emerged in our distant ancestors, followed by mutations associated with mental disorders.

This notion has intrigued me for years, rooted in the observation that wild animals, including our close relatives like chimpanzees, do not appear to suffer from serious mental illnesses such as schizophrenia or bipolar disorder. Perhaps our brains operate at the edge of our neural capabilities. Like a finely-tuned sports car, we can excel but are also prone to breakdowns. While still a hypothesis, this concept is difficult to shake off.

Oh, one more point. Although we often shy away from discussing methodological advancements, as readers generally prefer results, we made an exception in May. Alexandra Morton Hayward and her colleagues at the University of Oxford developed a method to extract proteins from ancient brains and potentially other soft tissues. Though such tissues are rarer in the fossil record compared to bones and teeth, some remain preserved and may offer a wealth of information. The first results could be available next year.

Source: www.newscientist.com