Linda Sutherland

This New Scientist article, usually accessible only to subscribers, is made available for free by the Museum of Applied Arts and Sciences in Sydney, Australia

FOR more than 3000 years the Egyptian pharaoh Merneptah’s body lay in the Valley of the Kings on the west bank of the Nile. In 1898, his mummified remains were taken to Cairo and a few years later the eminent Australian anatomist and Egyptologist Grafton Elliott Smith examined them. Smith described Merneptah as “an old man… almost completely bald, only a narrow fringe of white hair… remaining on the temples and occiput”. But his autopsy revealed something much more fascinating. “It indicated Merneptah had atherosclerosis,” says cardiologist Randall Thompson at the University of Missouri-Kansas City. To say that he and his colleagues were sceptical when they discovered this would be an understatement. “We didn’t believe it.”

Their incredulity is not surprising; atherosclerosis is generally thought of as a modern scourge. A chronic disease involving inflammation of the arteries, it is associated with high blood pressure, high cholesterol and heart attacks, and is the most common cause of death across much of the world today (see diagram). Along with cancer – the second biggest killer – and certain mental illnesses including depression, atherosclerosis is widely attributed to the stresses and excesses of a typical Western, post-industrial lifestyle. So what on earth was Merneptah doing with one of the triad of “diseases of civilisation”?


“Almost every type of cancer that afflicts us today has been documented in human remains from the past”

Convinced that Smith must be wrong, Thompson and his colleagues decided to take a look for themselves. In doing so, they have discovered that atherosclerosis is not new at all. Neither, it would seem, are the other main diseases that plague modern life. Understanding why, and to what extent, these conditions affected our ancestors challenges our beliefs about modern diseases.

Despite the assumptions, until recently nobody knew how prevalent atherosclerosis was in the past. In 2009, spurred on by their scepticism of Merneptah’s diagnosis, Thompson and his colleagues decided to look for evidence of the disease in mummies from the Museum of Egyptian Antiquities in Cairo. Using whole-body CT scans they searched for blockages, known as plaques, in the walls of arteries – a sure sign of atherosclerosis – and were surprised to find them in nine out of 16 mummies, including Merneptah. Here was the first clue that heart disease was a major player in ancient cultures. However, the team acknowledged that theirs was not a representative sample of ancient Egyptians; all were high-status individuals, well fed and possibly leading quite sedentary lives. What about other populations with different diets and lifestyles?

Good diets, bad hearts

In work published earlier this year, Thompson and colleagues offered an answer. This time they examined 137 mummies dating from 3000 BC to the 20th century, from four pre-industrial societies around the world: ancient Egypt, Peru, Utah and the Aleutian Islands in the Pacific Ocean. They also considered risk factors for atherosclerosis, especially diet, noting that the Egyptians consumed a version of the healthy “Mediterranean diet”, the peoples from Peru and Utah were farmers and hunter-gatherers, eating a wide variety of foods, without any of the dairy products or processed sugars that have been implicated in heart disease. The diet of the Aleutian Islanders was rich in oily fish, thought to reduce the risk of cardiovascular disease.

To the team’s surprise, CT scans revealed a high prevalence of atherosclerosis in all four populations (see diagram). It was present in 34 per cent overall, and in around 50 per cent in those aged over 40 (The Lancet, vol 381, p 1211). “That’s in the same ballpark as the prevalence of disease today,” says Thompson.

These findings are still open to the objection that only higher-status individuals were mummified. Still, the high frequency of plaques in people from diverse cultures suggests that atherosclerosis is far from modern. Perhaps there were different risk factors in ancient times, like smoke from cooking fires or higher incidence of infections, they say. However, the researchers conclude that it is also possible that humans have a “basic predisposition to the disease” (see “Any human heart“). Genes may play a bigger role than we think, says Thompson, and atherosclerosis may even be a normal part of ageing. He believes this has vital implications for preventing and treating it today. “The results are eye-opening, and should lead us to look beyond traditional risk factors,” he says. “Clearly the cause of the disease is multifactorial – and we know how to prevent it less well than some would have us believe.”

If heart disease was common among our ancestors, then what about cancer? In 2010, a review of studies involving tens of thousands of ancient skeletons and hundreds of mummies found little evidence of tumours. The researchers concluded that this supports the idea that cancer is a modern disease caused by pollution, unhealthy diets and Western lifestyles. But it is not that simple. True, the modern world contains carcinogens that were absent in pre-industrial times, but there are also many natural causes of cancer to which our ancestors would have been exposed, including ultraviolet radiation from the sun, radon from rocks and certain viruses. Not to mention the genetic component of cancers. If evidence of cancer in ancient human remains is sparse, that is no surprise according to David Frayer at the University of Kansas in Lawrence. “Many cancers kill people before there is an effect on bone and many cancers never have an effect on bone.” Limitations in scanning technology before 2005 may also help to account for the low rates of cancer found in ancient specimens.

Besides, such discoveries are not unheard of. Earlier this year in Croatia, Frayer’s team found what they say is the oldest known tumour in the human ancestral line, in the rib of a Neanderthal who lived 120,000 years ago. It was not cancerous, but there are ancient cases of malignant tumours in humans. The oldest are found in 5000-year-old human remains from Egypt and what is now Kentucky. And the first evidence of prostate cancer is 2700 years old, from a Russian king.

It makes sense that our ancestors would get cancer. A disease triggered by damaging mutations in DNA, cancer is likely to have been around ever since complex life evolved. In fact, the earliest clear evidence of a malignant tumour is found in a dinosaur dating from around 150 million years ago. If cancers are more common today, one reason is simply that people live longer. About 90 per cent of ancient human remains come from people who died before the age of 55, yet today 89 per cent of cancers are diagnosed in people over the age of 50. Cancer may be on the increase, but it is certainly not new; almost every type of cancer that afflicts us today has been documented in human remains from the past.

Prehistoric minds

If atherosclerosis and cancer are old foes, so too might be depression, attention deficit hyperactivity disorder (ADHD) and autism.

Today, around 15 per cent of people in developed countries and 11 per cent in less developed countries get depression at some point in their lives. It is not easy to track depression back in time, not least because definitions have changed. But however you characterise it, depression is not new, according to Clark Lawlor at Northumbria University in Newcastle, UK, author of From Melancholia to Prozac: A history of depression. For example, the Puritans in 16th and 17th century England were famous for being miserable. Lawlor also doesn’t buy into the idea that depression must be a product of modern living because it is virtually absent in traditional hunter-gatherer societies. The Zuni tribe of Arizona certainly do get depressed. “It can be admirable for them to be in an apparently severe condition of resignation and passivity,” he says. “If they wandered into a clinic in the US they would call it major depressive disorder.”

Lawlor is not alone in his views. Paul Andrews at McMaster University in Ontario, Canada, and his colleagues even suggest that natural selection has favoured depression because, in mild forms, it increases rumination and analysis and so might aid in the solving of complex problems.

This is highly speculative, but a similar evolutionary argument has been made to explain the prevalence of ADHD. It was not even recognised before the 20th century. Today, in the US, between 3 and 7 per cent of children are diagnosed with the condition, the hallmarks of which are inattention, hyperactivity and impulsivity. These traits can be problematic in the schoolroom but in the world of our ancestors, they might have made the difference between life and death, says Peter Jensen at the Mayo Clinic in Minnesota. Hyperactive individuals would have been better at foraging and spotting opportunities and threats. Impulsivity would have given them an edge when pouncing on prey and dodging predators, he argues.

Then there’s autism. First described in 1943, the diagnosis began to soar two decades ago. Now, more than 1 per cent of people in western Europe and the US have an autism spectrum disorder (ASD) – a range of conditions affecting behaviour, social interaction and communication skills. It looks like a classic modern development, but recent research indicates that the perceived increase is the result of heightened awareness of ASD and an expansion of the criteria used to diagnose it. But some think autism’s origins may be much older.

A focus on detail, strong categorisation skills, and an enhancement in certain types of visual memory are all attributes of some people with ASD. This was true for our ancestors too, argue Barry Wright at Hull York Medical School and Penny Spikins at the University of York, UK. Spikins thinks she has found signs of an autistic trait in the archaeological record. About 75,000 years ago in India, minuscule tools called microliths appeared. “The kind of precision and patience you need to make this technology is huge,” she says. Shift to Upper Palaeolithic Europe, between 50,000 and 10,000 years ago, and you get the Taï Plaque, a calendrical notation system, on which somebody has painstakingly marked the phases of the moon over several months. In the same era, highly realistic cave art appears – with a few examples looking a lot like the drawings of some savants today.

Spikins and Wright are now preparing a paper in which they argue that such behaviours coincide in the archaeological record with the timing of genetic mutations associated with some forms of ASD.

Viewing ASD, ADHD and depression as ancient adaptations casts them in a different light. Likewise, understanding that heart disease and cancer are not necessarily consequences of a modern lifestyle may empower people to make better health choices. Meanwhile, a better understanding of the origins and history of “modern” disorders could fundamentally change the way researchers and doctors view these problems – even if it means accepting that what they thought they knew was wrong.

Any human heart Heart attacks caused by atherosclerosis are the number one killer in most developed countries today, and the idea that it is a disease of modern life seems to be supported by evidence from chimps. In wild chimps, heart disease is rare, yet it is one of the main causes of death among captive individuals whose diet, lack of exercise and stress levels are more similar to those of modern humans. However, when Ajit Varki and Nissi Varki at the University of California in San Diego, took a closer look they discovered something remarkable. In humans, heart attacks generally happen when atherosclerosis blocks blood flow in the coronary artery. Captive chimps have many of the indicators for bad cases of the disease, such as high cholesterol and high blood pressure. “A human with that kind of profile would be considered at very high risk,” says Ajit Varki. Yet coronary blockage is rare. Instead, heart attacks in chimps are usually caused by rhythm problems arising from an excess of fibrous tissue in the heart muscle. “This was a big surprise.” It turns out that orang-utans and gorillas also get chimp-like fibrotic heart disease, suggesting that it affected the common ancestor of all great apes, which includes us. Somehow during our evolution, we have managed to shrug it off, but then, it seems, we evolved a different route to heart disease – atherosclerosis. That might mean that the key to our susceptibility to heart disease lies in biological differences between us and other great apes. Researchers in the Varki lab are now homing in on these. Their findings could provide new insights into the origins of atherosclerosis in humans, and potential new targets for treating the disease.

This article appeared in print under the headline “Ancient afflictions”