The German Primate Center (Deutsches Primatenzentrum) reports on a recent finding that researchers think sheds light on how the human brain got to be so large. They think the enlargement depends in part upon the work of two genes:

Two specific genes that evolve exclusively in humans jointly influence the development of the cerebrum. Researchers have provided evidence that these genes contribute together to the evolutionary enlargement of the brain … “How did the large brain evolve?,” March 26, 2025

Image Credit: Sorat - Adobe Stock

But how?

At Anthropology.net, Kambiz Kamrani offers a lay-friendly discussion of the research. Briefly, the researchers studied brain gene development in mice, chimpanzee brain organoids, and children aborted around eleven weeks:

Mouse Models: Introducing human versions of these genes into mice resulted in an increase in neural progenitor cells, suggesting a direct link between gene function and brain expansion.

Chimpanzee Brain Organoids: By cultivating miniature brain-like structures from chimpanzee stem cells, the researchers observed how the absence of these human-specific genes limited neural progenitor proliferation.

Human Brain Tissue Analysis: Further supporting their findings, the study examined human fetal brain tissue to confirm the expression patterns of NBPF14 and NOTCH2NLB in early brain development.

“The Evolutionary Roots of the Human Brain: How Two Genes Shaped Our Cognitive Landscape,” March 28, 2025

Michael Heide, the study’s lead researcher, notes,

”The remarkable feature of our study is that the results from animal experiments and alternative methods complement each other well and mutually confirm their findings. This not only emphasizes the high significance of our results, but could also help to reduce the need for animal experiments in the future by further developing, refining and confirming alternative methods.”Large brain evolve?”

He doesn’t specify whether the alternative methods will involve the use of more material from aborted children rather than animals, which are protected by research protocols.

But what exactly does the research show?

From the open access paper:

The remarkable expansion of the cerebral cortex over the past ≈2 millions of years of human evolution culminated in the strongly folded human neocortex, which is three times larger than that of our closest living relative, the chimpanzee. This tremendous increase in the size of the human neocortex is thought to be a basis for our higher cognitive abilities. A key process underlying the evolutionary expansion of the neocortex is cortical neurogenesis, which typically occurs during fetal development and involves cortical neural stem and progenitor cells (cNPCs). [citations omitted]

Nesil Eşiyok, Neringa Liutikaite, Christiane Haffner, Jula Peters, Sabrina Heide, Christina Eugster Oegema, Wieland B. Huttner, Michael Heide. A dyad of human-specific NBPF14 and NOTCH2NLB orchestrates cortical progenitor abundance crucial for human neocortex expansion. Science Advances, 2025; 11 (13) DOI: https://www.science.org/doi/10.1126/sciadv.ads7543

Kamrani offers,

This study adds another piece to the puzzle of human brain evolution, but many questions remain. How did these genes originate and become unique to humans? What other genetic or environmental factors contributed to the increase in brain size over millions of years? Future research will continue to probe these mysteries, combining genetic analysis with fossil and archaeological evidence to paint a more complete picture of our evolutionary past.

With each discovery, the story of human brain evolution becomes clearer, offering a deeper appreciation for the genetic symphony that shaped our species’ most defining trait—our intelligence. “Shaped Our Cognitive Landscape”

These are thoughtful questions. Underlying them though is a confusion that we are expected to take for granted: The human brain is confused with the human mind.

Human brain vs. human mind

While it is quite true that the human brain is very large by animal standards, there is no simple one-on-one relationship between overall brain size and intelligence.

And, as neurosurgeon Michael Egnor and I discuss in our forthcoming book, The Immortal Mind (Worthy June 3, 2025), humans can behave normally despite a variety of unusual brain challenges — split brain, half a brain, or a partially shared brain (true for some conjoined twins).

Obviously, some brain problems destroy the mind’s ability to connect with the world. But the fact that many such problems do not have that effect should warn us against a simple conflation of brain and mind.

Second, the way questions about the human brain (and mind) are formulated takes for granted that they evolved. Thus, the evidence that argues for stasis (no real change) may actually be taken for evidence of evolution instead. And even when we must admit that we have no idea how certain genes, unique to humans, came to exist, we are expected to assume that they evolved from earlier, simpler ones.

Many people who think this way would be surprised (and probably indignant) if they were told that their behavior is exactly what we have learned to expect from the adherents of a faith that may not be questioned. It doesn’t mean that they can’t do good science or make discoveries. But there will be certain conclusions they can’t come to no matter what the pattern of the evidence. Time will tell how important that evidence will prove to be.

You may also wish to read: Abstract reasoning in human ancestors: Earlier than thought? Researchers say, bone tools were being mass produced 1.5 million years ago in the in Olduvai Gorge in Tanzania. The question naturally arises, was the normally developed human mind ever incapable of abstract thought? That’s a challenge to accepted evolution theories.