Convergent evolution: The case of tenrecs and true hedgehogs

At first glance, a spiny tenrec from Madagascar looks almost identical to a hedgehog from Europe or Africa. Both are small, nocturnal mammals with pointed snouts, round bodies, and sharp spines covering their backs. Both roll into a tight ball when threatened, presenting predators with a prickly shield. It is easy to assume they must be close relatives. Yet this is not the case. Hedgehogs and tenrecs belong to entirely different evolutionary lineages. Their striking resemblance is the result of a process known as convergent evolution.

What Is Convergent Evolution?

Convergent evolution occurs when unrelated species evolve similar traits because they face similar environmental pressures or ecological niches. Instead of sharing these traits through common ancestry, they arrive at them independently through natural selection. The result is often animals that look and behave alike but are genetically distant.

Famous examples include the wings of bats and birds, which evolved separately for flight, or the streamlined shapes of dolphins and sharks, which help them move efficiently through water despite being mammals and fish.

Hedgehogs and tenrecs provide another classic case of convergence; spines and defensive behaviour that arose twice in separate parts of the mammalian tree.

Hedgehogs and Their Relatives

True hedgehogs belong to the family Erinaceidae, within the order Eulipotyphla, which also includes shrews and moles. Their spines are modified hairs made stiff with keratin, forming a coat of natural armour. Hedgehogs evolved in Eurasia and Africa, adapting to habitats ranging from woodlands and grasslands to suburban gardens.

Their evolutionary strategy centres on defence: rather than fleeing, they curl into a ball, protecting soft underparts and presenting only spines. Combined with an insect-based diet, nocturnal habits, and solitary lifestyle, this strategy has served them well across a wide distribution.

Tenrecs and Their Diversity

Tenrecs, by contrast, belong to the family Tenrecidae, within the order Afrosoricida. They are found almost exclusively in Madagascar, with a few species on mainland Africa. Tenrecs are famous for their diversity: some resemble shrews, others otters, and a few, like the lowland and streaked tenrecs, look remarkably like hedgehogs.

These spiny tenrecs evolved quills similar in appearance and function to hedgehog spines. They, too, roll up when threatened, relying on passive defence rather than flight. Yet genetically, they are no closer to hedgehogs than elephants are to manatees. Their resemblance is not kinship but coincidence shaped by natural selection.

Why Did They Evolve to Look the Same?

The answer lies in similar ecological pressures. Both hedgehogs and spiny tenrecs are small, slow-moving, ground-dwelling insectivores. Lacking the speed of a rodent or the burrowing power of a mole, they needed another way to deter predators. Spines, a low-maintenance armour made from modified hairs, provided an effective solution in both Europe and Madagascar.

Rolling into a ball further enhanced this strategy, maximising spine coverage and minimising vulnerability. Over millions of years, natural selection in two different environments arrived at the same design, because it solved the same problem.

More Than Just Spines

The convergence between hedgehogs and tenrecs extends beyond their quills. Both share:

• A nocturnal lifestyle, reducing competition and predation.
• Insectivorous diets, feeding on worms, beetles, and other invertebrates.
• Solitary habits, with individuals meeting only to breed.

These similarities reinforce the illusion of close kinship, yet their internal anatomy and genetic makeup tell a very different story.

Why It Matters

Understanding convergent evolution helps us appreciate the adaptability of life. Nature does not follow a single blueprint; it experiments, and when different lineages face similar challenges, they may converge on similar solutions. The resemblance between hedgehogs and tenrecs is not proof of shared ancestry, but rather of evolution’s creativity and efficiency.

For conservation, this distinction is vital. Protecting hedgehogs in Europe requires very different strategies from conserving tenrecs in Madagascar. They may look alike, but their habitats, threats, and ecological roles are unique.

In Summary

Hedgehogs and tenrecs are lookalikes born of convergent evolution. Spines and the ability to curl into a ball evolved twice in distant corners of the mammalian tree, driven by the same need for protection in small, slow-moving insectivores. Their story is a reminder not to judge kinship by appearance alone and a powerful example of how evolution finds similar answers to life’s recurring challenges.