Why Do Male Lions Have Manes? What the Mane Really Signals

How the mane grows

The mane is the most recognizable feature of the male lion. It is a thick ruff of long hair that can cover the head, neck, shoulders and chest, and sometimes extends along the belly. Its color ranges from blond and tawny to rust, dark brown and almost black.

The mane depends on the male hormone testosterone. It starts growing when young males reach adolescence, at around one year old, and keeps growing and darkening for several years, usually reaching full size at about four or five years old. If testosterone levels fall, the mane shrinks. Castrated males, for example, lose most or all of their manes.

Lions are the only cats with such a striking difference between the sexes. Researchers estimate that the mane evolved within the last few hundred thousand years.

The mane as a signal of fitness

The strongest evidence comes from long-term research on Serengeti lions, published in the journal Science in 2002. The researchers compared males with different manes and found clear patterns:

• Darker manes belonged to males that were older, better nourished and higher in testosterone. Their wounds also healed faster.
• Longer manes reflected fighting success and condition. Males that had been injured often grew shorter manes for a time.
• Females preferred dark manes. When the team placed life-size toy lions with different manes in the field, lionesses approached dark-maned dummies more often.
• Males avoided dark manes. Male lions were more cautious about approaching dummies with dark manes, as if treating them as stronger rivals.

Because a dark, full mane is hard to grow and keep unless a lion is healthy, it works as an honest advertisement. A female choosing a dark-maned male is likely choosing a strong partner able to protect her cubs from rival coalitions.

The cost of a mane: heat

A big, dark mane comes at a price. The same Serengeti study used thermal cameras and found that dark-maned males had hotter body surfaces than light-maned males, which means a heavier heat load. Manes were also shorter and lighter in hotter seasons and regions.

Climate shapes manes across the lion’s range. Lions kept in zoos in cooler parts of Europe and North America often grow larger, darker manes than wild lions in hot savannas. This trade-off between attractiveness and overheating helps explain why mane size varies so much.

Maneless lions of Tsavo and West Africa

In some places, many adult males have little or no mane. Kenya’s Tsavo region, a hot, dry area of thorny scrub, is the best-known example; the two lions that attacked railway workers there in 1898 were maneless males. Short-maned or maneless males are also common in Pendjari National Park in Benin and have been reported in Senegal and Sudan.

Researchers suspect several reasons. A heavy mane may be costly in intense heat, and thorny bush can snag and tangle long hair. These lions are still the same species; they simply grow different manes.

Maned lionesses in Botswana

Lionesses do not normally grow manes, but a few in northern Botswana, especially in the Okavango Delta, have developed short manes. Some of these females also roared and scent-marked more like males and did not breed. Scientists think they produce unusually high levels of testosterone, which triggers mane growth. Similar cases have occasionally been seen in zoos, sometimes linked to hormone problems.

Does the mane protect the neck?

For a long time, many people believed the mane evolved mainly as armor, protecting the neck and throat from bites and claws during fights between males. It seems a reasonable idea, but the evidence does not support it as the main function.

When researchers examined wounds on Serengeti lions, injuries were not concentrated around the neck and shoulders,. The mane may soften some blows, but its role as a signal is much better supported than its role as a shield.

Why manes matter to lion society

Manes make sense because of the way lions live. Males compete in coalitions to win control of prides, and takeovers often decide whether their cubs survive. A clear signal that lets lions judge a rival without fighting, and lets females judge a partner at a glance, saves time and injuries.

The mane is also visible from far away across open grassland, where lions live and meet rivals. Together with roaring and scent marking, the mane is part of a whole system of long-distance signals that lions use to avoid unnecessary fights. See how lion prides work and how long lions live for more on why male life is so competitive.