Human beings are a social species. From the earliest times, individuals have needed to cooperate in order to survive, and we still do. We are not alone in this — most animals have social interactions and rely on cooperation.

Although animal friendships have been derided as anthropomorphism, research has now shown that some animals do form long-term, stable relationships just like human friendships.

Of course, not all animals have such friendships — as far as we know, these are restricted to those that live in stable social groups, such as higher primates, elephants and cetaceans, such as whales and dolphins.

The basis of friendship is to value one another — each individual offers something that is valuable to another individual.

As humans, we value others for all sorts of reasons. They might like the same things we do, they might have similar political views, or perhaps lend help with work or chores.

Once we decide that we value someone, more often than not we will work at maintaining that friendship.

Speaking with Medical News Today, Dr. Scott Kaiser, a geriatrician and director of Geriatric Cognitive Health for the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, had this to say about friendship’s role in the evolution of humanity:

“Research suggests that evolution has continually selected for increasing social connection with social interaction and networks playing a major role in the survival of people. According to this framework, our ancestors formed social connections — working together, sharing food, and otherwise helping each other—to feel safe and protected.”

“Humans are hardwired to connect and social connections are an essential part of good health and well-being — we need them to survive and thrive, just like we need food, water and oxygen,” said Dr. Kaiser.

As children, most of us find that it is easy to make friends, but adults can find it more challenging. The good news is that the benefits of childhood friendships stay with us well into adulthood.

In one study, boys were followed up at the age of 32. Those who reported having had lots of friends in childhood had lower blood pressure and were more likely to be a healthy weight than those who were less sociable.

And it is not just close friendships that are good for us. People of all ages benefit from any type of social interaction. A 2017 study into “SuperAgers” — people in their 80s who have the memory skills of those several decades younger — found that they had far greater levels of positive social relationships than those with cognitive abilities expected for their age.

According to a 2014 study, “loneliness is caused not by being alone, but by being without some definite needed relationship or set of relationships.”

The study went on to suggest that loneliness can lead to many psychiatric disorders, such as depression, personality disorders, alcohol use and sleep disorders, and may even contribute to physical health problems.

So does socializing help protect against mental health disorders? Almost certainly, as Lee Chambers, psychologist and founder of Essentialise Workplace Wellbeing, told MNT.

“Having friends,” he noted, “has the potential to protect us from the impact of loneliness, and having effective friendships can buffer us from the adverse effects of loneliness.”

But what is an effective friendship? According to one study, high-quality friendships are more likely to be characterized by support, reciprocity, and intimacy.

Effective friendships provide a strong sense of companionship, mitigate feelings of loneliness, and contribute to both life satisfaction and self-esteem.

And there is a positive feedback loop between social relationships and self-esteem — each reinforces the other. So friendships boost self-esteem, which is a protective factor for both physical and mental health.

Lack of social interaction affects not only our mental health. Studies have shown that a low quantity or quality of social ties is linked to many medical conditions, such as cardiovascular disease, high blood pressure, cancer and impaired immune function.

“Social isolation and loneliness have negative health impacts on par with obesity, physical inactivity, and smoking 15 cigarettes a day, and are associated with about a 50% increased risk of dementia. Simply taking a moment [to] connect with someone — even through a brief phone call — can reduce feelings of loneliness, anxiety, and depression and deliver brain-protecting benefits.”

– Dr. Scott Kaiser

A 2010 meta-analysis of 148 studies — looking at the data of 308,849 people in total — found that participants with stronger social relationships had a 50% higher chance of survival over an average of 7.5 years than those without.

This study concluded that “[s]ocial relationship–based interventions represent a major opportunity to enhance not only the quality of life but also survival.”

Chambers agreed:

“Studies have shown that strong friendships can lessen risk factors for poorer long-term health, including waist circumference, blood pressure, and inflammation levels. Emotional support plays a big factor in this, with having somebody to listen, validate feelings and be a positive distraction an important structure in modern life, alongside the encouragement and support to adopt healthier behaviors and improve health outcomes.”

That support and encouragement can benefit even those who like to exercise. A 2017 study in medical students found that those who undertook a weekly group exercise class had significantly lower stress levels than those who did the same amount of exercise alone.

So all the evidence suggests that socialization benefits both our mental and physical health. But why? The key could be oxytocin.

Oxytocin is a hormone and neurotransmitter, produced in the hypothalamus. It is involved in childbirth and lactation, but is also associated with empathy, generosity and trust, all of which are key factors in friendships.

One study found that oxytocin was vital for social recognition in rodents, and this effect was also seen in people. Another, where researchers administered oxytocin to people via a nasal spray, found that this increased trust and made them more willing to accept social risks.

But why does oxytocin have physical benefits? These are likely to be due to its effect on cortisol — the stress hormone. Participants in a study who received oxytocin intranasally had lower levels of cortisol than those who received a placebo when subjected to the stress of public speaking.

The adrenal glands release cortisol when a person is under stress. This is good for emergency situations as it prepares us for action, but bad when it occurs long-term. Among other things, long-term high cortisol can cause high blood pressure, type 2 diabetes, and fatigue.

So keeping cortisol levels down is a good idea. That is where socialization comes in. When we are relaxed during positive social interactions, our bodies release oxytocin, so cortisol levels drop, and perhaps with them, also our blood pressure.

“Connection matters, but it’s not just about sheer numbers — amassing the most possible friends on your favorite social media platform or in the real world — but about the quality of those connections and enjoying the invaluable benefits of meaningful, supportive relationships.”

– Dr. Scott Kaiser

We all enjoy time to ourselves, and some friendships can have a negative influence on our health and well-being, but there is plenty of evidence that supportive relationships do us good.

So even the loners among us should recognize that getting out and connecting with people can make us happier and healthier, and it might even make us live longer.