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They were big, brutish and probably not particularly good-looking. Now it seems that Neanderthals had to contend with an ailment that affected their appearance too - psoriasis.

A new genetic study has suggested that these now extinct ancient cousins of modern humans may have suffered from the skin condition that causes red, flaky - and often painful - patches of skin.

The research has also revealed that they may have suffered from other modern medical disorders such as Crohn's disease, a condition that affects the digestive system.

Neanderthals, like the one above, are thought to have been broad-browed and big nosed but they may also have suffered from the skin condition psoriasis and Crohn's disease according to the latest DNA research

It suggests that the two diseases may have originated in a common ancestor of Neanderthals, Denisovans and modern humans more than a million years ago.

Researchers say the genetic changes that link the vulnerability to these diseases may even once have conveyed a benefit to our ancient ancestors.

This, they argue, may be why the diseases, which are both caused by inflammation triggered by the immune system, have persisted in the genome.

However, such negative traits can persist through evolution if they do not harm a species survival.

Dr Omen Gokcumen, an evolutionary geneticist who led the work at the University at Buffalo, part of the The State University of New York, said: 'Our research shows that some genetic features associated with psoriasis, Crohn's disease and other aspects of human health are ancient.

'Crohn's disease and psoriasis are damaging, but our findings suggest that there may be something else — some unknown factor now or in the past — that counteracts the danger when you carry genetic features that may increase susceptibility for these conditions.

'Both diseases are autoimmune disorders, and one can imagine that in a pathogen-rich environment, a highly active immune system may actually be a good thing even if it increases the chances of an auto-immune response.'

The researchers, whose work is published in the journal Molecular Biology and Evolution, compared modern human genomes to other closely related species including chimpanzees, Neanderthals and Denisovans.

Neanderthals are thought to have lived between 280,000 to 40,000 years ago before dying out completely while the Denisovans are thought to have been a sister group to Neanderthals, splitting from a common ancestor around 600,000 years ago.

The researchers looked for sections of DNA that had disappeared from the genomes since humans began diverging from chimpanzees - known as deletions.

They found 427 deletions in modern humans that were also in the genomes of Neanderthals and Denisovans.

Psoriasis is a common skin condition that can cause a rash and flaky or blistery skin (like above) anywhere on the body in modern humans but it may have been a problem for ancient human relatives like Neanderthals

The TV documentary Walking with Neanderthals portrayed the extinct ancient human species (above) as they are commonly seen based on their skeletons but their DNA has also suggested they suffered from psoriasis

By tracing when these deletions may have occurred, by looking at changes in the DNA, the scientists found that about 87 per cent of the deletions occured before modern humans and Neanderthals split from a common ancestor.

They found around nine per cent of the deletions found in modern humans probably came from interbreeding between Neanderthals.

Indeed, previous research has shown that modern humans in Europe owe around two percent of their DNA to Neanderthals due to interbreeding between the species in the past.

Much of what we know about Neanderthals has come from examining their bones, like the skull above, but now DNA extracted from their fossilised remains is helping to shed new light on what their lives were like

Psoriasis is caused by excessive inflammation in the upper layers of the skin by the immune system, causing the skin to thicken, form pustules, bleed and flake off in crusty clumps, as is shown in the diagram above

Neanderthals, like the one depicted above, are thought to have had a common ancestor with modern humans around a million years ago

Some research has suggested that genes we inherited from them could have changed our immune systems while also left us vulnerable to diseases like diabetes and cancer.

The new study found 17 gene deletions that code are thought to code for proteins. 

Most of these are involved in metabolism, growth and sperm development that were probably responsible for some of the changes that occurred as human ancestors evolved from chimpanzees.

However, the researchers also found examples of missing DNA that are known to play a role in causing psoriasis and Crohn's disease.

This would have meant that both Neanderthals and Denisovans suffered from both of these diseases.

Psoriasis can lead to itchy and sometimes painful rashes and blisters on the skin while Crohn's Disease is a chronic inflammation of the digestive system that can cause diarrhoea and stomach pains.

Dr Gokcumen said that while these are currently seen as negative diseases in modern humans, they may have provided some benefit to our ancestors.

He said the best example of this is sickle cell anemia, a disorder of the red blood cells that can makes it harder for them to carry oxygen around the body, but also prevents infection by the malaria parasite.

Yen-Lung Lin, who is the lead author of the study, added: 'We're thinking forces that maintain variation might be more relevant to human health and biology than previously believed.'