2.9. Monkey Love

Obedience, conformity and conditioning. These areas of the mind are slightly cold to Harry Harlow.

Harlow, an American scientist, had intended to study rats but ended up studying rhesus monkeys in the late 1950s and early 1960s.

Rhesus monkeys are easy to upkeep in captivity and were also the first primates to be rocketed into space. The rhesus monkey is best known for helping to discover the workings of human blood.

However, Harlow was not interested in any these uses, he wanted the monkeys to research love.

The First Rhesus Monkey Experiment

Imagine You are a rhesus monkey and you have just been born.

Your new born eyes are still closed.

The world is new to you.

And your world is Harry Harlow’s laboratory.

With outstretched tiny monkey hands you reach for your mother, ready to be lifted so she can see you. A pair of hands reaches down and picks you up.

Is this your mother?

You’re carried in arms and placed inside a cloth-towel covered wire cage. Apart from water and food, the cage is empty. Your mother is not here.

Nothing happens.

The world is now your cage and your world is empty.

You poke a tiny monkey finger through the wires of the cage and touch some soft cloth that is covering it.

A thought is triggered.

You’ve been detached from your mother and your animal instincts tell you that you need to be reattached.

So, without a mother, you need a substitute.

But what?

You look around your surroundings and ask what your substitute could be?

The Second Rhesus Monkey Experiment

Now imagine that You are not just one but a group of several newly born, rhesus monkeys. Like the monkey of the first experiment, you are taken at birth from your natural mother and placed in a cloth-towel covered wire cage.

However, this cage has two additional objects.

You see, with your monkey eyes, that there are two artificial mounds of wire crudely bent and twisted into the shape of mothers.

With the first artificial mother, the wire is naked and exposed. With the second artificial mother, the wire is covered in cloth.

Both artificial mothers each have a single nipple that supplies milk and water is plentiful. As a group of monkeys you have free will to choose which artificial mother to feed from.

Which do you choose?

The Results of the First Rhesus Monkey Experiment

Harlow first experimented on what it was like to be deprived of a mother at all.

As soon as newborn rhesus monkeys entered the world he took them away from their mothers and held them in empty cages.

He observed that the baby monkeys became extremely attached to the cloth towels that covered the cage. If a towel was attempted to be taken away the monkey would dig its fists into the soft material as hard as it could and struggle with all its might.

When the towel was taken away the monkey would cry just like a baby.

Why cry?

Before Harlow’s experiments, the previous understanding was that attachment was linked to the reward of nutrition. As babies, we love our mothers because their breasts provide milk. This is known as Drive Reduction. Hunger is a primary drive and so we want to reduce it.

Thirst and sex can also be viewed in the same terms. Drive Reduction went unchallenged through the 1930-1950s until Harlow saw the love his monkeys had for their cloths.

Why were they desperate to touch?

He needed to experiment further.

The Results of the Second Rhesus Monkey Experiment

Harlow took some wire cutters, cardboard cutters, coils, nails and soft cloth and created an artificial mother for his new born monkeys.

His surrogate mother was designed to have a similar size and shape to that of a real life adult monkey mother except for one major difference.

Instead of two breasts there should be one. The monkeys could suck on the breast and milk would be released.

With his team, Harlow took a group of baby rhesus monkeys and put them in the cage with the two surrogate mothers. He wanted to give his monkeys a choice. The first surrogate mother was his careful construction of metal and milk, and the second was a coil frame that was covered in the same cloth that covered the cages.

These were name the Metal Mother and the Cloth Mother, both capable of providing milk.

In their prisons, Harlow set his monkeys free to choose their mother and carefully observed the results.

Within a matter of days the rhesus monkeys had established a pattern of behaviour that was completely predictable. The monkeys had developed all their maternal feelings to the Cloth Mother and only went to the Metal Mother for milk when the Cloth Mother had run out.

Harlow also recorded that whereas with the Metal Mother, the monkeys would just feed from her when necessary, with the Cloth Mother the monkeys would stroke, pat and cuddle her.


Harlow had reasoned that love grows from touch not taste, which is why a mother’s milk dries up but the child continues to love her.

Man cannot live by milk alone.

The comfort of contact had been established as a key component of love.

When baby monkeys were placed in an unfamiliar room with their cloth surrogates, they clung to it until they felt secure enough to explore their cage. Once they began to explore, they would always return to the Cloth Mother for comfort and not the Metal Mother.

However, baby monkeys placed in an unfamiliar room, with their cloth-mothers removed, acted very differently.

Despite having access to milk from the Metal Mother, they would freeze in fear and cry, crouch down, or suck their thumbs. Some of the monkeys would even cry and scream.

They needed the Cloth Mother and their monkey brains would be tormented if they didn’t have her.

Once the monkeys reached an age where they could eat solid foods, they were separated from their Cloth Mothers for three days. After the initial pain and shock of losing their mothers, the monkeys would soon start to explore their surroundings. When they were reunited with their Cloth Mothers they clung to them like limpets and did not venture off to explore.

Harlow claimed from this that the need for contact comfort was stronger than the need to explore.

His study found that baby monkeys who were raised with either a Metal Mother or a Cloth Mother gained weight at the same rate.

However, the monkeys that had only a Metal Mother had trouble digesting the milk and suffered from diarrhea more frequently.

Love hurts when it’s made of metal.


Critics of Harlow’s claim that clinging is a matter of survival in young rhesus monkeys, but not in humans.

A monkey hangs from a tree, you don’t.

They argue that his conclusions, when applied to humans, overestimated the importance of contact comfort and underestimated the importance of nursing.

Not to mention all the animal abuse issues.

Do we learn from Harlow that we need to connect and communicate through touch at all costs?

Image from pradipparajuli.com.np

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