This particular romance may have ended in heartbreak, but Silo and Roy aren’t unique: over half a dozen zoos around the world are home to pairs of “gay penguins”, many of which have successfully reared chicks. Wild seabirds may also be that way inclined: a study of Laysan albatrosses in Hawaii reports that 31% of pairs were female-female, raising chicks that had been fathered elsewhere. A few years ago, Labour MP Dawn Butler stated that “90% of giraffes are gay”; though this claim was roundly trashed, it seems to contain a kernel of truth, in that male giraffes have indeed been seen engaging in behaviour that looks a lot like gay sex — at least as often as they have been observed mating with females.

Same-sex couplings are everywhere in the animal kingdom, as I learned this month at a Royal Society conference dedicated to discussing possible explanations for the seeming biological paradox of same-sex sex. On the face of it, it’s a behaviour that doesn’t make sense in evolutionary terms: an exclusive preference for the same sex is a trait that’s not likely to be passed on to offspring. Even opting for same-sex partners just some of the time requires an explanation: there would seem to be a huge evolutionary advantage in focusing one’s attentions towards the opposite sex, since it would make you more efficient than a competitor who mates indiscriminately.

Theories vary hugely depending on the species and context. Insects, for instance, just may not have particularly sophisticated methods of detecting partners of the opposite sex. If your entire brain is little more than a cluster of nerves, then some cases of mistaken identity are perhaps inevitable. At the other end of the spectrum, sex has a complex social function in species like primates. Our close relatives the bonobos frequently have group sex sessions that make human attempts at polyamory and pansexuality pale in comparison. In this species, what was once an adaptation purely for reproduction has taken on an additional role in maintaining both opposite-sex and same-sex social bonds, a bit like how our tongues initially evolved for tasting and swallowing food, but are now also indispensable in allowing us to speak. It’s different again in seabirds, where the care of chicks is a co-operative enterprise requiring hard work and trust between two pair-bonded adults. If “lesbian” albatross couples are effective at raising their chicks together when there aren’t enough males to go round, then why shouldn’t they?

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This abundance of teachable examples has been valuable to those wishing to refute claims that same-sex attraction is “unnatural”: clearly, it’s anything but. But there’s only so much we can learn from animals about why humans are sometimes gay. Although lots of animals mate or form partnerships with members of the same sex, this generally seems to be a flexible behaviour — as demonstrated by the fickle Silo. Our species is almost unique in that, across cultures, a small but consistent proportion of people seem biologically hardwired from a young age to desire only same-sex partners.

We know this is partially genetic: if your identical twin is gay, there’s roughly a 30-40% chance that you will be gay as well, compared with 1-2% in the general population. But how this gene manages to be passed on is a mystery, given that historically same-sex attracted people are significantly less likely to reproduce. For a while, a popular idea was that perhaps genes which predispose men to be attracted to other men or women to women persist because their relatives, who also carry the gene, somehow have more offspring as a result; either because the gene itself helps them somehow, or if childless gay uncles and aunts help to look after children. This idea was always quite far-fetched though, and unsurprisingly it has very little empirical support.

Another explanation could have something to do with reducing competition between siblings: if your brother is gay, you can be sure he’s not going to steal your girlfriend. It’s thought that this could be mediated in utero through the maternal immune system, since men who have older brothers are significantly more likely to be gay. There isn’t really any direct evidence supporting the hypothesis, either.

To me, this is one of the most fascinating unsolved mysteries of evolutionary biology. But not all biologists think so. The paradox of same-sex orientation receives disproportionately little attention from academic biology. Not only that, but some seem to be actively averse to researching why some animals are same-sex attracted. (This summary of research at Yale notes that “scientists rarely if ever actively study how often [same-sex behaviours] occur compared with different-sex sexual behaviours”.) So I was intrigued when I saw the Royal Society conference advertised. So much so that I shared it in a WhatsApp group of researchers from my department, in case it was of interest to others.

If I had given it a moment’s thought, I could have predicted the response. The event did not go down well. It “raised alarm bells”. Some discussed writing a letter to complain to the Royal Society. Other biologists wrote on Twitter that the event “could very easily go into YIKES territory” and “sent some red flags up” due to the Royal Society’s track record of giving an award to “a TERF” — referring, I assume, to neuroscientist Professor Sophie Scott, who won the prestigious Michael Faraday prize in 2021. (The conference was tiny, with only about 30 people in attendance, including the speakers and organisers.)

One reason many biologists think the discipline should steer well clear of this area is to avoid any politically inconvenient results. The finding that sexual orientation seems to be innate — in other words, not a choice — has been a core part of the gay rights movement. It turned a debate about whether certain behaviours were moral into a debate about civil rights for a marginalised group. Our support for gay marriage shouldn’t depend on how sexual orientation is determined, of course; but pragmatically speaking, the message that people are “born this way” has been enormously effective at changing hearts and minds. The wide range of “gay animals” in nature has been key in shoring up this argument: the internet is full of listicles like this one by PETA entitled, “Gay Animals Who Prove Same-Sex Love Is Natural”.

In my experience, academic biologists with adjacent specialties tend to see it as not their place to comment on this area, and view it as potentially suspect to show too much interest in it. To some, asking why some people — or even animals — are attracted to the same sex is the same as asking them to justify themselves, which gay people shouldn’t have to do of course. (One comment I saw in response to the Royal Society conference made exactly this claim.) On top of this, there is a perception that the relevant groups must be deferred to as the ultimate authority on any social issue. Taken to the extreme, this can mean that anyone else who presumes to scientifically study their characteristics is seen as politically incorrect. See, for instance, controversies in archaeology where genetic research becomes problematic if it threatens to contradict the origin myths of indigenous groups. Research into sexual orientation is similar, in that it challenges the moral right for LGBT people to have the final word on LGBT issues.

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Of course, it’s much easier to let others who care more decide what the facts are than to weigh in yourself. Many biologists, I think, would rather their work were relevant only in the academic niche in which they find themselves; few are comfortable commenting on politically sensitive subjects. But biology — the science of who we are and what our place is in the world — has much to say about the most pressing political and moral debates of our age. It is a shame if some of the people most qualified to contribute — often qualified at great public expense — are opting out of the conversation because they see it as too political.

Science is meant to be about striving to better understand our world, just because it’s interesting, “because it’s there”, because we can. For politicised areas, a dose of plain, unmotivated interest is especially needed. If we stigmatise whole realms of research, well-meaning scientists will avoid showing an interest in sensitive topics, and only those with an axe to grind remain. Scientists must actively commit to protecting curiosity for curiosity’s sake. Asking why the sky is blue need not carry the subtext that it ought to be some other colour instead.

“If I have seen further, it is by standing on the shoulders of giants.”

So wrote Isaac Newton in a letter to his fellow scientist Robert Hooke. But what appears to be an eloquent appeal to humility is anything but. Ironies drip from its layered meanings like custard from a vanilla slice.

The context is one of rivalry. As so often, the two men were in dispute as to who had thought of an idea first. Newton was downplaying the issue by suggesting that all progress is largely owed to achievements of our forebears – so why squabble over the little that the living might add to the sum total of human knowledge?

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Some scholars interpret Newton’s reference to ‘giants’ as a sly dig at the physically unimposing Hooke. Certainly, there’s the implication that seeking recognition for the originality of one’s ideas is the petty obsession of small men. But that’s all rather convenient for Newton, whose high reputation – though hardly undeserved – has been enhanced by having other people’s achievements attributed to him.

Appropriately enough, the shoulders of giants line is not really his. In fact, it dates back to the Middle Ages (and perhaps earlier to ancient Rome) Here’s the 12th-century version (attributed to Bernard of Chartres by John of Salisbury):

“Bernard of Chartres used to compare us to dwarfs perched on the shoulders of giants. He pointed out that we see more and farther than our predecessors, not because we have keener vision or greater height, but because we are lifted up and borne aloft on their gigantic stature.”

But there’s a bigger irony here. Hooke, Newton and the other ‘natural philosophers’ of their era were so much more than inheritors of an ancient tradition. In fact, they stood at the beginning of something wholly new – the great endeavour that we today call science.

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Nullius in verba was the motto of the Royal Society founded in 1660. It means ‘on the word of no one’ – a rejection of argument by authority in favour of evidence obtained by experiment.

This was a profound break with the past. For the first time in the history of thought, the dwarves had permission to not only stand upon the shoulders of giants, but also – if the evidence required it – to topple them over. It was a scientific revolution – the Scientific Revolution, in fact.

It’s hard to over-estimate Hooke’s role in all of this. Indeed, he spent much of his life (and centuries thereafter) being under-estimated. As a mere curate’s son from the Isle of Wight, he was of humble birth and modest means. Nevertheless, in 1653, at the age of 18, he managed to secure a place at Oxford.

His intellectual and practical talents won him various roles in service to scholarly gentlemen, including the founders of Royal Society. In 1661, Hooke was appointed as the Society’s curator of experiments, a role in which he worked with skilled craftsmen to develop the technology on which scientific progress really does depend – telescopes, microscopes, vacuum pumps and many other scientific instruments.

While others looked on, he got his hands dirty – doing more than anyone to ensure that science in its formative years stayed honestly experimental.

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He was a great theoretician as well a great experimentalist. What we now call Boyle’s Law of gases and Newton’s First Law of Gravitation can be more fairly attributed to Hooke – as are the engineering principles that allowed Christopher Wren to build the dome of St Paul’s Cathedral. Some of his more speculative ideas foreshadowed the scientific knowledge of much later times – the theory of evolution, plate tectonics and the study of how memory is formed.

Hooke did get credit for naming the ‘cells’ that are the building blocks of living creatures – which he observed through the microscopes he invented. In 1665, he published Micrographia, in which his brilliant drawings gave the general public with their first view of life at the microscopic scale. It was, quite rightly, a sensation – Hooke had unveiled a hidden world and in the process invented popular science.

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The following year, something else of great importance was ignited – the Great Fire of London. Raging over four days it consumed almost everything between Temple Bar in the west and the Tower of London in the east. It did, however, stop just short of Gresham college – HQ of the Royal Society and home of Robert Hooke.

The college was commandeered by the Corporation of London. The fellows of Royal Society decamped to the safety of Oxford, but Hooke was asked to stay. Faced with greatest challenge in the Corporation’s history, it was him they turned to for help.

City fires were a perennial danger in medieval and early modern Europe, but the conflagration of 1666 was on a scale that would not be exceeded until the 20th century. Witnessing the extent of the devastation, a despairing Samuel Pepys feared that London would never be rebuilt.

Over 13,000 houses were destroyed, 87 churches, the medieval St Paul’s cathedral, the Royal Exchange, three city gates and much else. Though 80,000 people were homeless, their houses weren’t quite razed to the ground, but lying in heaps of rubble that obliterated the streets. Even today, the country would struggle with such a disaster, so how did the fragile government of a deeply divided Restoration England, surrounded by enemies, cope?

The answer is that they just got on with it.

With astonishing rapidity the key decisions were made and stuck too. Schemes to reshape the city around grand radiating boulevards or a grid-like pattern of streets and avenues were swiftly drawn up and just as swiftly rejected. Rather than pre-empting the future development of Paris or New York, London chose to remain London – but a better version of London.

The established street pattern was retained, but key thoroughfares widened and the steepest gradients ameliorated. Property rights were respected, but replacement buildings had to be constructed out of brick and stone. Tenants paid for the reconstruction of their homes, but landlords accepted decades of greatly reduced rents. It was one of the great compromises of history – reconciling tradition and modernity.

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All very wise and farsighted; but while Hooke played his part in the counsels of the mighty, he was also on the ground making things happen. Indeed, before the scorched earth had even cooled, he and his helpers were out on the streets (or what used to be the streets) clearing away rubble and physically staking out the outlines of the new city that would rise from the ashes.

His tireless work helped settle disputes – securing support for the realignment of street plans and boundaries through meticulous surveying and scrupulous accounting. And if that weren’t enough, he found time to design several of the City’s new churches and other grand buildings (including the help he provided to Wren on St Paul’s ).

With Wren he also designed the Monument to the Great Fire of London – which is similar in form, but older and taller than the better known Nelson’s Column. In a typically Hookean flourish the Monument incorporated a zenith telescope, while the new cathedral was equipped with an observatory.

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How much of a difference did Robert Hooke make in his life? If he’d succumbed to his frail health as a child how much of a hole would that have left in the subsequent history of science and London?

Hooke, his towering intellect allied to superlative craftsmanship and relentless effort, was throughout his career a unique and vital link between theory and practice, idea and experiment, thought and action.

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I don’t think it too fanciful to suppose that he greatly accelerated both the progress of science and the reconstruction of London. Furthermore, his twin achievements compounded one another – catalysing the emergence of England as a world power.

He deserves a more prominent place in our national story than he’s received. Indeed for most of the three centuries following his death in 1703 he was all but written out. Newton, who became President of Royal Society (also in 1703), played a part in that – and possibly the mysterious disappearance of Hooke’s portrait. It is only in much more recent decades, thanks to the work of scholars like Alan Chapman, Lisa Jardine and John and Mary Gribbin that his true greatness has been rediscovered.

It was Chapman who described him as “England’s Leonardo”. Hooke is worthy of the comparison, but it’s a shame that he needs to be compared to anyone. He should be remembered for his own sake – a giant who stands in no one’s shadow.