Survival of the unfittest

From allergies to diabetes, the modern diseases that plague us were unknown to our hunter-gatherer forebears. So what can we learn from them?

As recently as 600 generations ago, our species were hunter-gatherers. They would walk and run nine to 15km a day. They would eat fresh food that was high in fibre and low in sugar. And they would spend much of their time nursing, napping and resting. Even simple everyday items such as shoes, books, and chairs were unknown. Quite different to modern day life, then.

Dan Lieberman, a professor of human evolutionary biology at Harvard University, argues that our 21st-century lifestyles are out of synch with our Palaeolithic bodies, and that is leading to trouble. We might be living longer than ever before, with lower infant mortality rates, but we are also prone to a huge number of problems, ranging from less serious ailments such as flat feet (from wearing shoes), having to wear glasses because of the rise of myopia (caused by all that reading), and lower back pain (those damn chairs), to the increase in allergies, as well as far more serious diseases such as diabetes, obesity, heart disease and certain types of cancer. Most of these, until recently, were extremely rare or even unknown, and, what's more, many are preventable.

Lieberman's new book, The Story of the Human Body: Evolution, Health and Disease argues that if you want to find solutions to these modern ailments, you have to consider evolution. “Nothing in biology makes sense except in the light of evolution, and that includes the good and the bad things about being a human today,” insists Lieberman. “We can't change the bodies that we inherited. We're stuck with them, like it or not. But by understanding and thinking about the evolutionary origins of our anatomy and physiology, we can think our way through better ways to prevent that kind of illness.”

It is worth remembering, he notes, that we live in the healthiest era ever for the human body and we should be proud of our achievements, especially the past few hundred years of medical science. “Basically, we shouldn't abandon modern life. That said, we are experiencing an epidemiological transition in which more and more people are getting sick from long-term chronic diseases that used to be rare. We evolved, over millions of years, bodies that are adapted for a particular lifestyle, and we get sick from diseases that are what we call mismatched diseases, which are caused by our bodies being inadequately or poorly adapted to the environments in which we now live. Of course, we treat those mismatched diseases by focusing on their symptoms, rather than their causes, perpetuating a vicious cycle, causing what I call dysevolution.”

Take osteoporosis, for example, which currently affects more than a third of women and one in five men in the UK during their lifetimes. This is a perfect example of “dysevolution” and, quite simply, is caused by the decline in physical activity necessary to build and maintain enough bone mass to last a lifetime. “We have skeletons that require exercise and physical activity to grow properly. That's an ancient aspect of our biology that we're not going to be able to change,” explains Lieberman. “We can't develop bone after we mature, so people achieve peak bone mass sometime between the age of 20 and 30, and the more active you are when you're young, the more bone mass you accrue in your body. Then we all start losing bone, that's just life. The rate at which you lose bone is accelerated by physical inactivity because you need to use your bones to keep them, just like you need to use your muscles to keep them. If you don't do enough physical activity when you're young, you won't develop enough bone mass to sustain your skeleton for a long and healthy life. And then we remain inactive as we age, and we lose that bone faster than we otherwise would do so, leading to osteoporosis.”

Because we have not figured out a way to increase bone mass, by the time someone is diagnosed with osteoporosis, it's too late and the disease needs to be managed. But it is, on the whole, preventable. “I'm not arguing that we shouldn't treat the disease,” adds Lieberman. “But we should also look at evolution because that tells us what to do: increase physical activity, especially in children.”

Quite often, this shift from infectious diseases to chronic ones is seen as “the price of progress”, and many doctors attribute this to advancements in healthcare resulting in an ageing population. But Lieberman insists that this doesn't need to be the case. Similarly, the rise in allergies is often connected to the increased use and advancements of antibiotics.

“Your immune system evolved to protect you from all those germs in the outside world, and we still have the same immune system; we didn't suddenly turn off our immune system after we invented sanitation, toilets and antibiotics. They're still there, primed and ready in your body looking for invaders to attack. But now we live in an environment where we remove many of those invaders.

“The decline in demand of the immune system causes it to sometimes behave inappropriately and attack cells or seemingly harmless molecules such as the proteins in peanuts or milk or wheat, and the result is an increase in the number of allergies and other immune disease.”

While Lieberman is not opposed to the use of antibiotics and antibacterial sanitation, he does suggest that we should use them wisely. “There's a cost every time you use them; they change your microbiome – all the animals that are inside you. Every time you use an antibiotic, you're nuking your internal environment and that has a cost. It's a reasonable hypothesis – although the evidence is not conclusive – that the rise in allergies and auto-immune diseases is because of the abnormal way in which we now allow our immune systems to function.”

The growing rate of diseases ranging from heart disease to diabetes is worrying, particularly as Lieberman points out that these are diseases virtually unknown among hunter-gatherers. Again, he believes them to be somewhat preventable. The answer? A change in diet and physical exercise.

The problem with physical exercise, Lieberman notes, is that our bodies are adapted to take it easy. “It's not just that walking is good for you because doctors say so, but we have bodies that evolved to be highly active. They weren't doing triathlons and marathons but they were moderately and sensibly active. Now we've removed a lot of that because of machines and various other technologies.

“But it's important to recognise that most hunter-gatherers are on the margin of energy bounds – they had barely enough energy given all the work they do. When they were struggling with food, it was not a good idea for them to go off on a 10 km jog for the hell of it; that's a waste of energy when you could otherwise use on staying healthy and having more offspring [which was the main thing our bodies were evolved to do].

“So we're adapted to take it easy if we can and enjoy comfort. I know I have to coerce myself into doing exercise. If we're going to turn this around we have to figure out methods to a collective action to help each other act in our own best self-interest. Even when our biology conspires against us.”

But what of the future? Lieberman argues that the main factors to consider in averting much of this ill health are our diet and exercise. “Right now, it's a bit gloomy. But it's not all dreadful and miserable. We're all living longer lives; we're doing quite well in many respects, but we also have rising levels of chronic diseases. The United States now spends nearly 20 per cent of gross domestic product on healthcare and other countries are catching up fast.

“That transition that we're currently going through is alarming and costly and means there's a lot of misery out there, particularly as people age. To some extent, it's because people are living longer: we mustn't confuse diseases that occur in old age with diseases that are caused by old age. To a large extent, we can live longer and be healthier at the same time, but that requires us paying attention to how our bodies evolved.

“We're a species that's capable of acting together and I think if we take effective collective action, it won't take much to turn this around,” he continues. “If we just promote a little bit more physical activity, we could completely reverse this trend in healthcare. Physical activity alone could do it. It's the closest thing we have to a magic bullet.”

'The Story of the Human Body: Evolution, Health and Disease', by Daniel Lieberman (Allen Lane, £16.99) is out now

Life and Style
ebookNow available in paperback
ebooks
ebookPart of The Independent’s new eBook series The Great Composers
Arts and Entertainment
The teaser trailer has provoked more questions than answers
filmBut what is Bond's 'secret' that Moneypenny is talking about?
News
Johnny Depp is perhaps best known for his role as Jack Sparrow in Pirates of the Caribbean
peopleBut how did he break it?
Arts and Entertainment
Paul Walker and Vin Diesel in Fast and Furious 5
film
Sport
Lewis Hamilton secured his second straight pole of the season
f1Vettel beats Rosberg into third after thunderstorm delays qualifying
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    Recruitment Genius: Massage Therapist / Sports Therapist

    £12000 - £24000 per annum: Recruitment Genius: A opportunity has arisen for a ...

    Ashdown Group: Practice Accountant - Bournemouth - £38,000

    £32000 - £38000 per annum: Ashdown Group: A successful accountancy practice in...

    SThree: Trainee Recruitment Consultant

    £18000 - £23000 per annum + Uncapped commission: SThree: Does earning a 6 figu...

    Recruitment Genius: SEO Executive

    £18000 - £25000 per annum: Recruitment Genius: This is an exciting opportunity...

    Day In a Page

    The saffron censorship that governs India: Why national pride and religious sentiment trump freedom of expression

    The saffron censorship that governs India

    Zareer Masani reveals why national pride and religious sentiment trump freedom of expression
    Prince Charles' 'black spider' letters to be published 'within weeks'

    Prince Charles' 'black spider' letters to be published 'within weeks'

    Supreme Court rules Dominic Grieve's ministerial veto was invalid
    Distressed Zayn Malik fans are cutting themselves - how did fandom get so dark?

    How did fandom get so dark?

    Grief over Zayn Malik's exit from One Direction seemed amusing until stories of mass 'cutting' emerged. Experts tell Gillian Orr the distress is real, and the girls need support
    The galaxy collisions that shed light on unseen parallel Universe

    The cosmic collisions that have shed light on unseen parallel Universe

    Dark matter study gives scientists insight into mystery of space
    The Swedes are adding a gender-neutral pronoun to their dictionary

    Swedes introduce gender-neutral pronoun

    Why, asks Simon Usborne, must English still struggle awkwardly with the likes of 's/he' and 'they'?
    Disney's mega money-making formula: 'Human' remakes of cartoon classics are part of a lucrative, long-term creative plan

    Disney's mega money-making formula

    'Human' remakes of cartoon classics are part of a lucrative, long-term creative plan
    Lobster has gone mainstream with supermarket bargains for £10 or less - but is it any good?

    Lobster has gone mainstream

    Anthea Gerrie, raised on meaty specimens from the waters around Maine, reveals how to cook up an affordable feast
    Easter 2015: 14 best decorations

    14 best Easter decorations

    Get into the Easter spirit with our pick of accessories, ornaments and tableware
    Paul Scholes column: Gareth Bale would be a perfect fit at Manchester United and could turn them into serious title contenders next season

    Paul Scholes column

    Gareth Bale would be a perfect fit at Manchester United and could turn them into serious title contenders next season
    Inside the Kansas greenhouses where Monsanto is 'playing God' with the future of the planet

    The future of GM

    The greenhouses where Monsanto 'plays God' with the future of the planet
    Britain's mild winters could be numbered: why global warming is leaving UK chillier

    Britain's mild winters could be numbered

    Gulf Stream is slowing down faster than ever, scientists say
    Government gives £250,000 to Independent appeal

    Government gives £250,000 to Independent appeal

    Donation brings total raised by Homeless Veterans campaign to at least £1.25m
    Oh dear, the most borrowed book at Bank of England library doesn't inspire confidence

    The most borrowed book at Bank of England library? Oh dear

    The book's fifth edition is used for Edexcel exams
    Cowslips vs honeysuckle: The hunt for the UK’s favourite wildflower

    Cowslips vs honeysuckle

    It's the hunt for UK’s favourite wildflower
    Child abuse scandal: Did a botched blackmail attempt by South African intelligence help Cyril Smith escape justice?

    Did a botched blackmail attempt help Cyril Smith escape justice?

    A fresh twist reveals the Liberal MP was targeted by the notorious South African intelligence agency Boss