Several hominid species — Australopithecus africanus, Paranthropus robustus, early homo varieties, Gigantopithecus brachy, Pongo, papio, homo neanderthalensis, and homo sapiens — have undergone significant lead exposure over two million years, as revealed by a new analysis of fossilized teeth collected from Africa, Asia, Oceania, and Europe. This finding challenges the notion that lead exposure is merely a contemporary issue.
Lead exposure affecting modern humans and their ancestors. Image credit: J. Gregory/Mount Sinai Health System.
Professor Renaud Joannes Boyau from Southern Cross University remarked: “Our findings indicate that lead exposure has been integral to human evolution, not just a byproduct of the industrial revolution.”
“This suggests that our ancestors’ brain development was influenced by toxic metals, potentially shaping their social dynamics and cognitive functions over millennia.”
The team analyzed 51 fossil samples globally utilizing a carefully validated laser ablation microspatial sampling technique, encompassing species like Australopithecus africanus, Paranthropus robustus, early homo variants, Gigantopithecus brachy, Pongo, papio, homo neanderthalensis, and homo sapiens.
Signs of transient lead exposure were evident in 73% of the specimens analyzed (compared to 71% in humans). This included findings on Australopithecus, Paranthropus, and homo species.
Some of the earliest geological samples from Gigantopithecus brachy, believed to be around 1.8 million years old from the early Pleistocene and 1 million years old from the mid-Pleistocene, displayed recurrent lead exposure events interspersed with periods of little to no lead uptake.
To further explore the impact of ancient lead exposure on brain development, researchers also conducted laboratory studies.
Australopithecus africanus. Image credit: JM Salas / CC BY-SA 3.0.” width=”580″ height=”627″ srcset=”https://cdn.sci.news/images/2015/01/image_2428-Australopithecus-africanus.jpg 580w, https://cdn.sci.news/images/2015/01/image_2428-Australopithecus-africanus-277×300.jpg 277w” sizes=”(max-width: 580px) 100vw, 580px”/>
Australopithecus africanus. Image credit: JM Salas / CC BY-SA 3.0.
Using human brain organoids (miniature brain models grown in the lab), researchers examined the effects of lead on a crucial developmental gene named NOVA1, recognized for modulating gene expression during neurodevelopment in response to lead exposure.
The modern iteration of NOVA1 has undergone changes distinct from those seen in Neanderthals and other extinct hominins, with the reasons for this evolution remaining unclear until now.
In organoids with ancestral versions of NOVA1, exposure to lead significantly altered neural activity in relation to Fox P2 — a gene involved in the functionality of brain regions critical for language and speech development.
This effect was less pronounced in modern organoids with NOVA1 mutations.
“These findings indicate that our variant of NOVA1 might have conferred a protective advantage against the detrimental neurological effects of lead,” stated Alison Muotri, a professor at the University of California, San Diego.
“This exemplifies how environmental pressures, such as lead toxicity, can drive genetic evolution, enhancing our capacity for survival and verbal communication while also affecting our susceptibility to contemporary lead exposure.”
Gigantopithecus blackii inhabiting the forests of southern China. Image credit: Garcia / Joannes-Boyau, Southern Cross University.” width=”580″ height=”375″ srcset=”https://cdn.sci.news/images/2024/01/image_12599-Gigantopithecus-blacki.jpg 580w, https://cdn.sci.news/images/2024/01/image_12599-Gigantopithecus-blacki-300×194.jpg 300w, https://cdn.sci.news/images/2024/01/image_12599-Gigantopithecus-blacki-84×55.jpg 84w” sizes=”(max-width: 580px) 100vw, 580px”/>
An artistic rendition of a Gigantopithecus brachy herd in the forests of southern China. Image credit: Garcia / Joannes-Boyau, Southern Cross University.
Genetic and proteomic analyses in this study revealed that lead exposure in archaic variant organoids disrupts pathways vital for neurodevelopment, social behavior, and communication.
Alterations in Fox P2 activity indicate a possible correlation between ancient lead exposure and the advanced language abilities found in modern humans.
“This research highlights the role environmental exposures have played in human evolution,” stated Professor Manish Arora from the Icahn School of Medicine at Mount Sinai.
“The insight that exposure to toxic substances may conjure survival advantages in the context of interspecific competition introduces a fresh perspective in environmental medicine, prompting investigations into the evolutionary origins of disorders linked to such exposures.”
For more information, refer to the study published in the journal Science Advances.
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Renaud Joannes Boyau et al. 2025. Effects of intermittent lead exposure on hominid brain evolution. Science Advances 11(42); doi: 10.1126/sciadv.adr1524
Source: www.sci.news
