Neanderthal fossil may be earliest evidence of disease jumping from animals to humans

Scientists find evidence of brucellosis in the most studied Neanderthal fossil to be unearthed

Virtual reconstruction of the skeleton found in La Chapelle-aux-Saints, based on high-resolution 3D surface scans of the spine and pelvis (Martin Häusler/UZH)

Scientists have found one of the earliest examples of a disease jumping from animals to humans while reexamining a Neanderthal fossil.

The specimen, known as the “Old Man of La Chapelle,” was unearthed in a cave near the French village of La Chapelle-aux-Saints in 1908.

It is the first nearly complete prehistoric human fossil to be unearthed and one of the most studied, said researchers, including Martin Haeusler from the University of Zürich in Germany.

Earlier studies found the human had died about 50,000 years ago when he was in his late 50s or 60s and that he had advanced osteoarthritis, the most common kind of arthritis, in his spinal column and hip joint.

But not all the deformities in the Old Man could be explained by the wear and tear caused by osteoarthritis.

In the new study published last month in the journal Scientific Reports, the scientists found that some of these pathological changes were due to inflammation caused by the bacterial disease brucellosis.

The disease infects cattle and humans contract it when they come in direct contact with infected animals, according to the World Health Organisation.

The scientists found characteristic signs of brucellosis in the pathogenic lesions and erosions on the backbone specimen of the ancient human, who belongs to the same hominin category as modern humans.

“This implies the earliest secure evidence of this zoonotic disease in hominin evolution,” the scientists wrote in the study.

Brucellosis, which is still widespread today, causes fever, muscle pain and night sweats that last for weeks to years. The researchers suspect it could have been transmitted to the Neanderthal through butchering or eating raw meat.

In many cases, the disease can also cause arthritis pain and inflammation of the testes that can lead to infertility, as well as inflammation of the heart valves – the most common cause of death from brucellosis.

It is one of the most common zoonotic diseases – illnesses transmitted from animals to humans – such as Ebola and Covid-19.

The bacteria that cause brucellosis, have been reported in a wide range of wildlife including wild sheep, goats, cattle, European bison, reindeer, and wild boar – animals considered important components of the Neanderthal diet, according to the study.

“Neanderthals likely were infected by brucellosis during butchering of prey animals, not unlike the abattoir experience today, or by eating raw meat,” the scientists wrote in the study.

But since the Old Man of La Chapelle lived up to his 60s – a very old age for the period – the researchers suspect he may have contracted a milder version of the disease.