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33 Interesting Facts About Monkeys You Probably Never Knew

Is there any difference between monkeys and apes? As it turns out, there is – apes have no external tails whereas monkeys do. That’s just one of the many interesting facts about monkeys you’ll find out as we explore some fun facts about primates

While monkeys and apes are both primates, they are members of different subdivisions of the higher primates depending on whether they are New World or Old World monkeys.

New World monkeys are classified in the parvorder platyrrhini, while apes and Old World monkeys are classified in the parvorder catarrhini.


With that in mind, let’s take a look at the two different types of monkeys: New World and Old World monkeys. The map above illustrates the distribution range of the New and Old World monkeys: Orange represents the New World Monkeys, red the Old World Monkeys.

Miss Baker with her Jupiter rocket

New World Monkeys

Within the platyrrhini parvorder, there are two main families: Callitricidae and Cebidae.

The Callitricidae family members, the marmosets and tamarins, are considered to be the most primitive primates because they do not have opposable thumbs, prehensile tails, or nails on all their digits.

While most New World monkeys give birth to a single infant, these monkeys primarily give birth to twins. The Callitricidae males shoulder most of the parenting duties include carrying the young, while females handle the parenting for the Cebidae.

The Cebidae family has four subfamiles: Aotinae, Atelinae, Cebinae, and Pithecinae and includes the following species

  • Howler monkeys (Atelinae)
  • Spider monkeys (Atelinae)
  • Night monkeys (Aotinae)
  • Tiki monkeys (Aotinae)
  • Squirrel monkeys (Cebinae)
  • Capuchins (Cebinae)

  • Sakis (Pithecinae)

  • Uakaris (Pithecinae)

8 Amazing Things About New World Monkeys

How many of these intriguing things about New World monkeys did you already know?

  • The marmoset is the smallest primate and weighs anywhere from five ounces to two pounds.
  • The Howler monkey is the largest New World monkey, weighing between 15 and 22 pounds. Their name comes from their loud howls, which can be heard over three miles away from the monkeys.
  • Of all primates, only Cebidae family members have prehensile tails.
  • The Cebidae have nails on all their digits.
  • New World monkeys live in trees for the most part and are herbivores.
  • Marmosets and tamarins are herbivores, but their preference is for tree sap, and they tend to live in areas where the trees are rich with their favorite food.
  • The brain of the capuchin monkey is the largest in relation to body size of any primates.
  • The night monkey is the only nocturnal primate.

2 Fast Facts: Famous Capuchin Monkeys


Capuchin monkeys have been used as service animals for quadriplegics, assistants for organ grinders and even starred on Hollywood’s silver screen:

1. Crystal: Dexter, the monkey from the hit movie Night at the Museum, was played by the Capuchin animal actor Crystal who also starred in:

  • George of the Jungle (1997)
  • Night at the Museum: Battle of the Smithsonian (2009)
  • We Bought a Zoo (2009)
  • The Hangover (2011)

According to TV Guide, Crystal was the highest paid animal actor starring in a television comedy. She earned $12,000 per episode. Unfortunately for the tiny monkey’s bank account, NBC cancelled the show on 10/18/2012.

2. Hellion: Up until the death of his master Robert Foster, the service animal Hellion did many helpful tasks which the quadriplegic could not do on his own. Hellion was trained by Mary Jane Willard as a service animal for disabled humans, and he and Foster were a team for over 25 years.

Hellion could vacuum, lock doors and even play music on a stereo. Other capuchins have been trained to help the disabled by performing tasks like cooking, bathing, feeding and even scratching itchy skin for their humans.

2 Space Pioneering Squirrel Monkeys


Miss Baker: Miss Baker was one of a pair of monkeys launched into space on a Jupiter mission project. She and her shipmate Miss Able earned their places on the honor roll of space flight experimentation by being the first two monkeys to be launched into space and return to earth to be recovered alive. (We’ll talk more about Miss Able, a rhesus monkey, when we examine Old World monkeys.)

Gordo: Gordo, a squirrel monkey also known as Old Reliable, left Earth on the spacecraft Jupiter AM-13, which achieved a height of 600 miles, but he did not survive the flight due to a malfunctioning parachute on the recovery system.

Old World Monkeys

Old World monkeys are primarily semi-terrestrial, unlike their cousins the New World Monkeys, and have nails on all their digits. They are typically larger than New World Monkeys with the exception of the Howler monkey, the largest New World Monkey, and on average are about the size of small or medium canines.

The parvorder catarrhini has two subfamilies: Cercopithecinae and Colobinae.

The Cercopithcinae family comprises:

  • Baboons
  • Guenons
  • Macaques
  • Mangabeys
  • Mandrills
  • Patas monkeys

4 Fun Facts about the Cercopithcinae

  • Males are larger than females. The scientific term for this is sexually dimorphic.
  • They are omnivores whose favorite foods are meat and fruit.
  • The Rh blood type system and Rh factor were named after rhesus macaques.
  • Macaques are used extensively in space and medical research.

The Colobinae family includes: colobus, langurs, and proboscis monkeys.

2 Fascinating Facts About the Colobinae Monkeys

Probiscis monkey

  • All Colobinae are vegetarians (herbivores).
  • Proboscis monkeys have long noses (think Pinocchio).

The two families are easily distinguished by identifying characteristics, according to Dennis O’Neill, who wrote the following in “Old World Monkeys.”

“The Cercopithecinae have ischial callosities, cheek pouches, and are omnivorous. The Colobinae are herbivorous and have sacculated stomachs as well as elongated intestines that efficiently process leaves high in difficult to digest cellulose.”1

Space Monkeys Tidbits

For over 50 years countries like Argentina, France, Russia/Soviet Union and the United States have used monkeys in their space flight programs. These monkeys were used to test the effects of weightlessness on living organisms as well as gauge the potential for sending living beings into space and then bringing them back to earth safely.

The New World monkeys typically used for rocket flight research were squirrel monkeys, with the most famous of these being Miss Baker and Gordo (aka Old Reliable). (See Miss Able and Miss Baker’s historic flight in the video below.)

Miss Baker outlived Miss Able, who died a few days after returning to earth, and NASA retired her to Huntsville, Alabama, where she outlived two husbands. Dying at the ripe old age of 27, she might have been the oldest squirrel monkey whose age was documented. Those wishing to pay their respects to Miss Baker can visit her grave in Huntsville, Alabama at the United States Space and Rocket Center, where it is a custom for visitors to leave a banana on her grave.

Miss Able and Miss Baker made their famous space flight on Jupiter AM-18. Although Miss Able survived the flight and return home, she died a few days afterward. Her preserved body can be seen at the Smithsonian Institute’s National Air and Space Museum.

Rhesus monkeys and pig-tailed macaques, which are all Old World monkeys, were also used for space flight. Some famous rhesus monkey astronauts were Miss Able, Albert I, and Albert II.

The first attempt to launch a monkey into space was the Albert (I) Project, manned by the rhesus monkey Albert. This space pioneer rode a V2 Blossom rocket 39 miles but did not survive the return to Earth.

Albert I was followed by Albert II, the first monkey to reach space. Unfortunately, he did not return alive either.

Patricia and Mike, Philippine monkeys, were the first monkeys launched in an Aerobee missile and recovered alive, but their flight did not go high enough to reach space. (See video below.) Their flight went for 36 miles, while the May 1959 flight of Able and Baker reached 300 miles, thus making them the first monkeys to go to space and return alive. Mike survived Patricia by 13 years.

Monkeys in Medical Research

According to the Humane Society of the United States, the monkey species used in medical research are:

  • Crab-eating macaques
  • Marmosets
  • Pig-tailed macaques
  • Rhesus macaques
  • Squirrel monkeys
  • Tamarins

Testing on these monkeys provides valuable data for medical researchers in a wide range of fields of study ranging from human diseases to psychological disorders to drug and vaccine research.

Rhesus monkeys are the species most often used for medical research because of their similarity to humans in anatomy and physiology. Additionally, they are low maintenance for upkeep and readily available.

Four facts about research on monkeys that you may or may know:

  • Tetra2 is the first primate to be cloned. The rhesus monkey was produced by artificially splitting embryo cells from a donor animal to create a genetically-identically monkey.
  • Rhesus monkeys (primarily macaques) were used in a controversial social isolation research project by Harry Fredrick Harlow. Some monkeys were kept in semi-social isolation and others in total social isolation. When the monkeys were taken from the total social isolation environment, they experienced emotional stress and/or manifested the type of behavior associated with autistics such as rocking.
  • In 2001, Oregon researchers succeeded in producing ANDi, the first transgenic primate, by introducing the Green Fluorescent Protein (GFP) gene into the DNA sequence of a rhesus monkey. The inserted gene occurs naturally in jellyfish. ANDi stands for “DNA inserted” spelled backwards.
  • Medical research on rhesus monkeys produced three vital vaccines: polio, rabies and smallpox.

This is only a small offering of the many interesting facts about monkeys. In fact, volumes of books have been written about the antics, research and benefits to mankind of these wonderful primates. If you’d like to find out more, a good place to start your research is at your local library.


  1. 1 – O’Neill, Dennis, “The Primates,” http://anthro.palomar.edu/primate/prim_6.htm
  2. Manning, Sanchez, Blame It on Crystal! Monkey Film Star Sparks New Craze, 09/02/2012
  3. Battaglio, Stephen and Schneider, “Who Earns What: TV’s Highest Paid Stars,” TV Guide, 08/08/2012
  4. Holguin, Jaime, “Monkey Provides a Helping Hand,” CBS Evening News, 12/05/2007
  5. Whitehouse, David, “Scientists ‘clone’ monkey,” BBC News, 14 January 2001
  6. Undisclosed author, “Questions and Answers About Monkeys Used in Research,” The Humane Society of the United States, 09/28/2009
  7. Trivedi, Bijal P., “Introducing ANDi: The first genetically modified monkey,” Genome News Network, 01/16/2001

Image credits:

  1. Baker and Jupiter rocket by unknown author under Public Domain via Wikimedia Commons
  2. Baker with merit certificate image by NASA under Public Domain via Wikimedia Commons
  3. Probiscis monkey by Drew Avery under CC-BY-2.0 via Wikimedia Commons
  4. Monkey distribution map by unknown author under CC-BY-SA 3.0 via Wikimedia Commons
  5. Capuchin image by Frans de Waal under CC-BY-2.5 via Wikimedia Commons

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