Having Neanderthal genes could make you more at risk from severe coronavirus, a study has found.
A genetic quirk inherited from the extinct human species, who lived 40,000 to 400,000 years ago, could make people more susceptible to Covid-19.
This genetic variation is present in modern-day humans because our ancestors had sex with Neanderthals about 60,000 years ago, researchers say.
And those who have the variant, found on chromosome three, are up to three times more likely to need ventilation if they catch the virus.
In a study of 3,199 hospital patients with coronavirus in Italy and Spain, researchers found the genetic signature was linked to a more severe illness.
Lead author Professor Hugo Zeberg, from the Karolinska Institutet in Sweden, said: ‘The increase in risk is 60-70 per cent if you carry one copy of the Neanderthal variant and three times the risk if you have two copies – one from your father and one from your mother.
‘Later studies estimate the risk increase to be even higher, with twice the risk if you have one copy and up to a five-fold increase if you have two copies.’
The gene variant had first been found in the remains of a Neanderthal in Croatia from some 50,000 years ago, and continues to be found in millions of modern day humans.
Neanderthals were a species that lived alongside humans tens of thousands of years ago and were very similar in appearance and size but were generally stockier and more muscular.
This primitive relative of humans existed for around 100,000 years – much of that time alongside people and breeding with them – before going extinct around 40,00 years ago.
It is not yet known why the Neanderthal gene is associated with an increased risk of becoming severely ill, while scientists say it is something to be investigated ‘as quickly as possible’.
Not everyone has this variant – it is most common among people of South Asian ethnicity, of whom around 50 per cent have it.
It is less common in Europe, where about 16 per cent of people carry it.
Bangladesh has the highest number of carriers at 63 per cent.
This difference may contribute to the differences in severity of Covid-19 that have been observed between different populations.
For example, individuals of Bangladeshi descent in the UK have about two times higher risk of dying from Covid-19 than the general population.
The researchers wanted to know whether the quirk had been passed over from Neanderthals or whether it had been inherited by both Neanderthals and present-day people through a common ancestor.
They concluded it must have come from inbreeding between Neanderthals and present-day humans because the last common ancestor between the groups would have lived 550,000 years ago – during which time the genetic variant probably would have been altered.
Author Professor Svante Paabo, from the Okinawa Institute of Science and Technology, said: ‘It is striking that the genetic heritage from Neanderthals has such tragic consequences during the current pandemic.’
The scientists are keen to point out that there are also other factors that can influence a person’s susceptibility to having a severe reaction to the virus, including their age and the existence of other medical conditions.
Professor Zeberg, said: ‘Obviously, factors such as your age and other diseases you may have also affect how severely you are affected by the virus.
‘But among genetic factors, this is the strongest one.’
The study was published as a pre-print in July and has now been peer reviewed and published in Nature.