International Primate Day

International Primate Day, observed each year on September 1, is a special day dedicated to raising awareness and celebrating the incredible diversity of primates—from tiny lemurs and tarsiers to powerful gorillas and orangutans—while highlighting the urgent need for their protection.

History of International Primate Day

International Primate Day was first established in 2005 by the British-based organization Animal Defenders International (ADI). Since then, it has been supported annually by a growing number of primate-focused advocacy groups around the world. The observance aims to give voice to all primates—both lower and higher—increasing global awareness of the threats they face, particularly in research institutions and fragile environments.

Over time, the day has become a valued educational opportunity. Zoos, sanctuaries, and conservation organizations worldwide have embraced International Primate Day with special events, educational programs, and public outreach designed to promote humane treatment and conservation of primate species.

Why is International Primate Day important?

Primates are not only our closest living relatives—they are also vital to the health of global ecosystems. Many primate species play irreplaceable roles in seed dispersal, forest regeneration, and ecological balance. Unfortunately, more than one-third of the world’s primates are either critically endangered or facing extinction due to habitat destruction, illegal hunting, and wildlife trade. And the urgency is growing fast.

International Primate Day invites us to reflect on the ethical dimensions of how humans treat these intelligent and social animals. It encourages us to support humane policies in research, protect their habitats from further destruction, and uplift conservation efforts. It’s a gentle yet powerful reminder that our choices today shape the fate of primates—and, by extension, the ecosystems we all share.

Here are a few heartfelt ways the day resonates:

• reminders that primates are individuals with emotions, families, and cultures
• showing that conservation isn’t distant—it starts with awareness and action
• trusting that small education efforts can ripple into meaningful change
• believing that protecting primates means protecting biodiversity itself
• feeling a connection to species we share a deep evolutionary bond with

Interesting facts about primates

• Primates with longer thumbs tend to have larger brains, suggesting that manual dexterity and cognitive ability may have co‑evolved across species. This correlation was found in a study examining 94 primate species.
• More than 60% of primate species are threatened with extinction, and 75% have declining populations due to habitat loss, poaching, and other human activities.
• Out of over 500 nonhuman primates, there are around 505 species living in the wild across 90 countries. The monkey population alone includes about 260 distinct species.
• Old World monkeys come from Africa and Asia, New World monkeys from the Americas. Their nostrils differ: Old World monkeys have narrow, downward-facing nostrils; New World monkeys have round, side-facing ones. Old World monkeys also tend to be larger and more ground-dwelling.
• The smallest primate in the world is the pygmy mouse lemur, weighing about 30 grams (1.1 oz), while Madagascar’s lemurs are among the most endangered primate groups.
• Galagos (bushbabies) are exceptional jumpers, capable of leaping great distances thanks to elastic tendon energy and remarkable strength in leg muscles—far outperforming frogs relative to body size.
• Chimpanzees demonstrate empathetic and healthcare-related behaviors, such as using leaves to wipe themselves, licking wounds, applying healing leaf poultices, and assisting injured peers. ¹
• Monkeys and apes diverged from a common primate ancestor around 23 to 34 million years ago, evidenced by both fossil and genetic studies.
• Many primate species rely on seed dispersal to regenerate tropical forests, playing a vital role in ecosystem health and carbon sequestration—important for combating climate change.
• Primates typically develop more slowly and live longer than similarly sized mammals, maturing later but enjoying extended lifespans due to their complex social and cognitive lives.
• Baboons live in large troops ranging from 8 to 200 individuals, with a highly organized structure. When moving, dominant males lead the group, females and young stay protected in the middle, and less dominant males follow behind. They use at least 10 different vocal calls to communicate. ²

• The word “lemur” comes from Ancient Roman mythology, where “lemures” referred to restless spirits or ghosts—an association made because of lemurs’ nocturnal and eerie movements.
• Lemurs use scent to communicate, with specialized glands on their wrists and behinds. They mark branches to claim territory and send messages to others.

• Capuchin monkeys are highly inventive foragers, known to use stone tools to crack nuts and extract edible resources. This tool use can take years to learn, with juveniles mastering it by about eight years of age.

• Mother chimpanzees often form lasting emotional bonds with their young, maintaining those relationships well into adulthood.
• Male gorillas use chest-beating as a bluff, not always as a threat—often it’s just a dramatic warning so others can retreat. They also use it during play.
• Wild gorillas are notoriously hard to study because they live secretive lives in thick, remote tropical forests and tend to avoid humans.

• The name “marmoset” comes from the French “marmouset”, meaning shrimp or dwarf—fitting for these tiny monkeys, especially the pygmy marmoset, the smallest true monkey.
• Marmosets use sharp teeth to gnaw tree bark, encouraging sap to flow out. The sap serves as a key source of nutrition, rich in carbohydrates and minerals.
• Scientists have found wild chimpanzees self-medicating, using forest plants to treat illness and injury. One such plant even contains compounds with anti-tumor properties.
• Spider monkeys use their strong, prehensile tails like an extra limb, and the tip has a unique, fingerprint-like pattern for gripping.

• Female spider monkeys have large clitorises, which can be mistaken for male genitalia. The clitoris also acts as a urine reservoir and plays a role in chemical signaling during mating readiness.
• Colobine monkeys (leaf-eaters) have sacculated stomachs, adapted for fermenting tough plant material. Bacteria inside help them break down cellulose-rich leaves and unripe fruits.
• Apes and monkeys differ in obvious ways: apes are larger, have no tails, walk more upright, and depend more on vision. Their noses are broad and flat, while many monkeys have snouts.

How to Celebrate International Primate Day

You don’t need grand gestures to honor International Primate Day—it’s about curiosity, compassion, and connection. You could start by reading about a particular primate species or watching a documentary that brings their stories to life. Sharing that knowledge with friends or on social media can spark important conversations.

If you have access to a zoo or sanctuary hosting a primate day event, consider attending. Keeper talks, interactive quizzes, and enrichment demonstrations offer fun, hands-on learning opportunities. For those passionate about conservation, donating to or supporting groups that protect primate habitats—especially in biodiversity hotspots like Madagascar, Indonesia, and the Congo Basin—makes a real difference.

Simple, genuine actions that people often take:

• learning something about a primate species you didn’t know before
• asking friends to pause and consider how our choices affect wild lives
• visiting an awareness event and experiencing primates up close
• supporting a conservation project—even just by donating or spreading the word
• sharing a fact or photo online to inspire others to care

International Primate Day Dates Table

1. https://www.theguardian.com/environment/2025/may/14/chimpanzees-use-leaves-to-wipe-bums-and-clean-up-after-sex-study-finds[↩]
2. https://seaworld.org/animals/facts/mammals/primates/[↩]