18/09/2025
PART 1 — HOW HORSES GOT INTO ONE SHOE
Picture North America some 55 million years ago. Forget open plains and galloping herds. What you’d find instead was a muggy, green world of swamps and dense forests, buzzing with insects the size of dinner plates. In the undergrowth darted a nervous little animal about as big as a fox terrier. It had four toes on the front feet, three on the back, and padded soles that looked more suited to a hedgehog than a hunter. This was Eohippus — the “dawn horse.” Although to call it a horse is rather like calling a dormouse a draft horse.
Eohippus was, at best, horse-ish. More deer-meets-rabbit, with a nervous twitch and teeth designed for browsing tender shoots rather than grinding tough grasses. It lived in the shadows, dodging predators, doing its best not to become a snack. No one looking at it then would have placed bets on its descendants winning the Grand National or pulling London omnibuses. Yet evolution, in its slow and opportunistic way, had other plans.
FROM FOREST BROWSERS TO PLAINS RUNNERS
As the climate shifted, forests began to retreat. Grasslands — vast, open, sun-scorched — spread in their place. Grass is a terrible food: low in calories, full of abrasive silica, like eating tiny shards of glass. Animals that could grind it survived. So horse teeth began to flatten, crowns lengthened, enamel folded.
The ground hardened too. Speed became salvation. A small herbivore out in the open was a walking buffet unless it could sprint. And sprinting on multiple wobbly toes wasn’t ideal. Extra digits became evolutionary dead weight. By about 37 million years ago, Mesohippus walked on three toes. In mud, that spread the load nicely. On hard ground, it was clumsy.
Fast-forward another 10 million years, and Merychippus appeared — larger, stronger, still three-toed, but with the middle digit beginning to dominate. It grazed, rather than browsed, and lived in herds on the plains. The horse, as we’d recognise it, was taking shape.
Then came Pliohippus, around 5 million years ago. This was the first true one-toed horse. Those side toes, once useful in swamps, had shrunk to splints. All the animal’s weight pressed through a single sturdy digit, wrapped in a thick, keratinised wall. At last, the hoof.
By the time Equus emerged roughly 4 million years ago, the evolutionary gamble was complete: a large herbivore, one toe per limb, built for endless miles at speed. The horse had arrived.
THE EVOLUTIONARY GAMBLE
It was an extraordinary solution. One toe allowed longer strides, faster gallops, and the endurance to roam for miles. A horse could outpace most predators. A hoof wore evenly across tough plains. Herds spread across continents.
But this marvel came at a cost. One toe is excellent for speed on firm ground, hopeless for variety. Horses became specialists. They traded versatility for efficiency. A three-toed horse could cope in mud, forest, or rock. A one-toed horse could outrun wolves — but struggled anywhere its design didn’t fit.
Evolution never plans ahead. It doesn’t ask, “What if someone keeps this animal in a damp stable on lush ryegrass?” It just solves the problem of the moment. For millions of years, that problem was surviving on the plains. And the one-toed hoof solved it brilliantly.
THE LEGACY IN TODAY’S HOOF
Every hoof you pick up today is shaped by that ancient compromise. The coffin bone (P3), crescent-shaped and porous, is the remnant of that single digit. The splint bones alongside the cannon are ghosts of toes long abandoned. The odd calluses of chestnuts and ergots may be echoes of ancient pads.
And the weaknesses remain too. Hooves designed for arid steppe struggle in wet winters. Metabolisms tuned for sparse forage collapse on fertilised pasture. The “perfect” hoof was never perfect — it was just good enough for a very specific set of conditions.
That is why modern hoof care is always a balancing act. We are managing an organ built for one world and forced to live in another. When horn crumbles, laminae inflame, or soles go soft, these aren’t design flaws. They are the inevitable mismatches between evolutionary history and domestic reality.
A COMPROMISE WE STILL LIVE WITH
So when you look at a horse’s hoof, remember what you’re really seeing. You’re seeing a 55-million-year experiment in survival. You’re seeing forests that vanished, grasses that spread, predators that gave chase, and millions of evolutionary near-misses where species died out.
The modern hoof is a miracle — and a gamble. It is both exquisitely adapted and hopelessly compromised. A tool built for speed and stamina, pressed into a life of stables, turnout paddocks, rugs, supplements, and farriers’ rasps.
That tension — between what the hoof evolved for and what we ask of it — is the heart of hoof care. Every trim, every shoeing choice, every management decision sits in that space. The one-toed horse won the evolutionary lottery, but the prize came with strings attached. Strings that we, 55 million years later, are still carefully unpicking.