What Happened to the Lion`s Mane? - ACCESS

What Happened to the Lion’s Mane?
The manes of male lions are often considered
to be symbols of strength and ferocity. No
other big cat has a mane like the male lion. In
fact, there are plenty of reasons why having a
thick mane is not a good idea. A thick mane
insulates, or traps heat, near the animal’s face
and neck. This makes it harder for the lions to
stay cool in the hot sun of the African
savannah. Also, the manes can get caught on
the thorny acacia trees found on savannahs.
Another disadvantage is that the manes make
the lions more conspicuous to other animals.
This can make it more difficult to sneak up on
prey. Finally, in a world where survival is
already tough, the energy required to grow a
mane may be better used for other functions.
The mane of a male lion (above) consists of
thick hair surrounding the animal’s head and
along its neck. Female lions (below) do not
grow manes.
Why Do Lions Have Manes?
Of all the big cats, lions are the most social.
Females live in groups called prides, while
males live in groups called coalitions. The
males in different coalitions compete for the
rights to breed with the females in a pride.
Research suggests that males with
magnificent manes are fitter, healthier, and stronger than
other males. The large mane is also intimidating to other
males. It is a visual signal that a particular male can protect
its pride and dominate its habitat. When male lions fight for
prides, the mane may help to protect the head and neck. It is
also possible that larger manes impress females. This may
make it easier for a lion with a large mane to take over a
pride.
Natural and Sexual Selection
Charles Darwin used the term natural selection to describe
how evolution occurs. If a trait improves an organism’s
chances of survival, that organism will be more likely to
reproduce and pass the advantageous trait to the next
generation. Over time, more and more individuals within a
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What Happened to the Lion’s Mane?
population will have the advantageous trait. This process is
an example of natural selection.
Darwin was puzzled by the features of some
organisms because they did not seem to result
from natural selection. Many species exhibit
traits that seem to hinder survival. Examples
include the long tail feathers of the male
peacock and the large antlers of some male
deer. Like the lion’s mane, these traits make
organisms more conspicuous (in the cases of
peacocks and deer, to predators). A peacock
with extremely large tail feathers will likely be
slower and less agile than smaller-tailed
males. Such a bird may be caught and eaten
before it can reproduce.
A male peacock has an impressive tail for
attracting mates. However, such a large
tail may make the peacock more
vulnerable to predators.
For organisms such as the peacock, Darwin
described a special kind of natural selection. He called it
sexual selection. In these cases, features that increase an
animal’s chance of breeding will persist, even if the feature
would seem to hinder survival.
Scientists who study animal behavior have found that there is
often a tradeoff between survival advantages and breeding
advantages. This seems to be the case with the male lion. A
large mane may be a burden, but it increases a male’s chances
of breeding.
The Lions of Tsavo
The male lions that live in Tsavo National
Park in Kenya tend to grow much smaller
manes than other lions. And Tsavo lions tend
to be several years older than other lions
before they begin to grow their manes. For
scientists, this has raised more questions
than answers. Why have these lions “lost”
their manes? Are they still sociable, and can
they still breed successfully?
Scientists thought for a long time that the
male lions they were seeing in Tsavo were
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This adult male lion at Tsavo National Park
has only a little extra hair around its cheeks
and neck.
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What Happened to the Lion’s Mane?
young males that had not yet grown their manes. Current
research shows that this is incorrect. Most male lions develop
full manes by age five. In Tsavo, however, males older than
eight have been discovered with only bits of extra hair
growing along their heads, chins, and cheeks.
In other mammals, such as humans, hair loss and hereditary
baldness have been linked to high levels of the hormone
testosterone. Scientists have hypothesized that the male lions
of Tsavo do not grow manes like other lions because they
have higher testosterone levels. The males at Tsavo live in
social groups until they are about six years old. At that age
testosterone levels peak. This can create conflicts between
males. Coalitions at Tsavo often break apart when the males
turn six. When a male lion leaves a coalition, it often roams
alone until it can take over a pride.
Some scientists have hypothesized that temperature is the
key factor in determining whether male lions grow manes.
Evidence from zoos suggests that when lions are kept in
captivity in hot places, they lose their manes, whereas lions
kept in cold places tend to grow thick manes. Tsavo National
Park is on average ten degrees hotter than the Serengeti. The
male lions that live in the Serengeti tend to have magnificent
manes.
Natural selection seems to be responsible for both maned and
maneless lions. In the cooler Serengeti, larger-maned males
gain females more easily and pass the trait for large manes to
their young. In this cooler climate, the mane is not a
significant disadvantage. In the hot climate of Tsavo,
however, maneless lions stay cooler and therefore have an
advantage over lions with manes. Because most of the males
at Tsavo are maneless, the presence of a mane does not
convey a significant breeding advantage. Scientists continue
to study the maneless lions of Tsavo to learn more about the
complexities of natural selection.
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