Pretty pleased with yourself? Won the war with your waistline, picked the right partner, scaled the career ladder and formed some unassailable political views along the way? Bad news. You can take less credit for your life choices (and even those beliefs you hold dear) than you might like to think.
We humans flatter ourselves that we are authors of our own destiny – masters of superior insight, willpower and rationale. In fact, we’re merely machines made flesh: operating under the necessary illusion of free will, while our subconscious circuitry is busy driving us down paths preordained by our genes.
This is the cheerful message of Cambridge neuroscientist Hannah Critchlow, who meets me at Magdalene College, damp-haired from her daily two-hour jog, to explain how her new book, The Science of Fate, shows that everything from what you eat, to who you marry and how you vote, may already be hard-wired into your brain.
A co-presenter for BBC’s Tomorrow’s World Live and Channel 4’s The Secret Lives of 4 and 5 Year Olds, Critchlow was dubbed the “female Brian Cox” by this paper after her headline-grabbing talk at Hay Festival in 2015, where she predicted humans would one day be able to upload their brains to a computer and, thus, live forever.
“I started off in a little tent and then more and more people were interested in coming, so I got bumped up and up into one of the largest stages,” she recalls of that debut, which got her this book deal.
“At one point, I was like: ‘Holy s---, I’ve gone over Irvine Welsh…’” Jude Law was in the audience, she learnt afterwards.
Last year, she wired up Dr Rowan Williams, former Archbishop of Canterbury, now Master of Magdalene, to a brainwave reader while he meditated on stage. This year, she will be dissecting Leonardo da Vinci’s studies of the brain with Germaine Greer, before attempting to answer the existential question our species has grappled with since, well, the dawn of humanity: “what – or who – is calling the shots?”
Though many of us concede that luck has played at least some part in our lives, the concept of fate has largely fallen out of fashion.
Instead, “a growth mindset permeates society”, Critchlow writes, “advocating that our every goal or desire can be achieved. We are sold the concept of unlimited agency and capability, a vision of free will on steroids that rejects the idea of constraints, whether biological or socioeconomic.”
She is of the steadily burgeoning counterview: that a complex dance between our genetic inheritance and experience means much of how our life unfolds is out of our conscious control. Our early years’ environment shapes us, too, of course, but science is uncovering a hereditary basis, she says, not just for our health, but our wealth – and even the age at which we lose our virginity.
As the mother of a three-year-old son, (she announced her pregnancy in her last Telegraph interview, it turns out – “I hadn’t even told my mum and dad at that point!”), doesn’t such biological determinism seem a bit bleak?
“Learning that things are quite written, and prescribed into, us can be very liberating,” she argues. Beyond being a good, healthy role model to her son Max, overanxious parenting is pointless: “A huge amount of his temperament, of his skills, of his differences” is already “done and dusted”.
Our DNA determines how our unique neural circuitry – or connectome, made up of some 100 trillion pathways – is laid down in the womb, she explains: priming us to see the world in our own bespoke way and informing, in turn, how we make the minute- by- minute decisions that ultimately shape the arc of our lives.
Studying our brain chemistry can even reveal political leanings. “People who vote in a more conservative way are much more likely to have a hyperreactive amygdala region of the brain, which is involved in fear response,” she says. If that helps to explain the Rorschach test that is Brexit, it doesn’t bode well for ever reaching a consensus.
Critchlow can envision a day when embryos might be screened for traits such as extroversion, agreeableness and openness to experience before they’ve even been born.
A massive project is already under way to scan, non-invasively, the brains of babies in the womb and observe their connectomes taking shape. Soon, technology will be able to follow an individual from before birth to death, mapping that brain circuitry as it develops and tallying it with behaviour and life trajectories.
Where will it end – with us being able to access our connectomes on our smartphones?
“Can you imagine?” she laughs. “Every time there’s a decision to be made: ‘Siri! What shall I do, here?’”
There are obvious dangers to neuro-hype. “It’s not helpful to suggest a single gene, single brain region or, indeed, single anything is responsible for any aspect of human behaviour,” Critchlow writes. In fact, there are up to 150 genes implicated in predisposing whether you’re lardy or lithe – including those that govern your sensitivity to hunger and pleasure – and up to 70 per cent of your body weight is estimated to be directly shaped by those that you’ve been dealt.
If, like half of the world’s population, you have a variant of one in particular – FTO, which instructs your body to keep on eating – you’re 25 per cent more likely to become obese. If you have two, as an unlucky sixth of us do, that doubles to 50 per cent.
What excites Critchlow is not uncovering people’s biological constraints – “though I don’t think it’s necessarily healthy to think that the world is our oyster” – but their potential.
At her own comprehensive school in Northampton, there was never any mention of Oxbridge: “I was talking about wanting to be a doctor and the careers advice was: ‘Well, maybe go be an optician.’”
Instead, she took a year out, and ended up working as a nursing assistant at St. Andrew’s Psychiatric Hospital, with teenagers who had been detained under the Mental Health Act.
It was there she realised she didn’t have the emotional resilience to be a doctor – “I just found it very upsetting” – but became hooked on the brain.
“Quite a lot of the children there had quite harrowing early life experience [of abuse and neglect] that actually quite a lot of the staff there had also experienced,” she says. Yet at the end of a 13-hour shift, the patients remained locked up, while the staff were able to go home.
“It made me really interested in what makes some people have one life trajectory and others another – what gives resilience, what helps a brain to flourish?”
After getting a first-class biology degree at Brunel University, she went on to do her PhD in neuropsychiatry at Magdalene, and is now has now come full circle as the college’s science outreach fellow, working with state-school students who – like her – may not otherwise have considered giving Cambridge a crack.
Besides education, she emphasises the ability of exercise and meditation to open our minds – “loads of neuroscientists” are heavily into jogging and yoga, she notes – and stimulate the neurogenesis of new neurons, just as chronic stress can kill them.
Above all, to paraphrase the teenage environmental campaigner Greta Thunberg, she believes each of our unique neural perspectives is a “gift” to the collective consciousness, which benefits us all.
Learning how little mastery we may have over our own minds “doesn’t detract from the way that we’re special as humans”, Critchlow says. “It actually, to me, makes it more beautiful, and more mesmerising – and it makes me accept other people a little bit more.”
Six ways to swerve fate, and slow ageing's effect on your brain
Dementia is one of the scourges of contemporary life – it’s estimated that 7.7 million people will develop the condition every year (writes Hannah Critchlow). There is a genetic component in a small proportion of cases and the NHS offers genetic screening for some high-risk families, but studies have also implicated lifestyle issues, including obesity, low physical-activity levels, depression, lack of social contact, smoking and leaving education early, as contributing factors.
Either way, the underlying mechanism causing the debilitating symptoms of dementia is nerve cells dying off. Until the late 1990s, conventional wisdom said that a person is born with all the neurons they’ll ever get, meaning that dementia was effectively a slow death sentence, impossible to evade.
But in a wonderful set of experiments, performed initially in mice, it was demonstrated that movement induced stem cells to develop into fully formed neurons through a process called neurogenesis. Even more incredibly, the simple act of combining physical activity with exploring a new environment and interacting with different individuals helped these newly born neurons to integrate fully into the existing circuit, to survive and flourish.
I asked Dr Rogier Kievit, research fellow at the Medical Research Council’s Cognition and Brain Sciences Unit, who has dedicated his career to investigating the ageing process in the general population, what he did to protect his own brain from its effects. We compiled a list of the things we can all do to build our brain’s resilience as we age. Top of the protection tips is, surprise, surprise...
1. Being physically active
It doesn’t have to be running. Thirty minutes of low-level work-out such as walking, swimming or cycling three times a week is great for the brain and body. Whatever your size, whatever your timetable, get out there and be physically active. It will not only potentially ramp up your neurogenesis but also keep your capillaries healthy.
2. Get a good night’s sleep
There is mounting evidence to show that sleep helps to consolidate connections between neurons, enabling a host of processes, such as turning new knowledge into banked memories. Sleep also gives your immune system the chance to clear away any toxins made in your brain during the day so that they are less likely to accumulate and kill off neurons.
3. Stay socially active
Spending time with friends and family, discussing things, learning from other people, taking on board their perspectives and ideas helps to keep your brain process dynamic and is generally associated with better wellbeing.
4. Check your diet
Any food that is associated with poor cardiovascular health (animal fats, processed foods, too much sugar) is also associated with poor cognitive health. The general rule is to eat for your heart and brain as one. This protects against micro-strokes that could asphyxiate neurons.
5. Keep learning
Learning early on in life helps to protect against cognitive decline in later life. Research shows that the longer people stay in education the more likely their brain will age healthily. But lifelong learning of any kind, inside or outside formal education, is a great strategy for maintaining brain health.
6. Stay positive
Better mental health is associated with better cognitive health: if you’re feeling blue you’re less likely to find the motivation for, or derive pleasure from, exercise, looking after yourself or getting out and about for social interaction. Writing a gratitude journal each night before you go to sleep makes it easier to wake up in a more motivated mood, keen to replicate some of the adventures you experienced the day before and seek out new ones.