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Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond

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An engaging and deeply reported investigation of friendship: its evolution, purpose, and centrality in human and nonhuman lives alike.

The bonds of friendship are universal and elemental. In Friendship, journalist Lydia Denworth visits the front lines of the science of friendship in search of its biological, psychological, and evolutionary foundations. Finding it to be as old as life on the African savannas, she also discovers that friendship is reflected in our brain waves, detectable in our genomes, and capable of strengthening our cardiovascular and immune systems. Its opposite, loneliness, can kill. As a result, social connection is finally being recognized as critical to our physical and emotional well-being.

With warmth and compassion, Denworth weaves together past and present, field biology and cutting-edge neuroscience, to show how our bodies and minds are designed to make friends, the process by which social bonds develop, and how a drive for friendship underpins human (and nonhuman) society. With its refreshingly optimistic vision of the evolution of human nature, this book puts friendship at the center of our lives.

312 pages, Hardcover

First published January 28, 2020

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About the author

Lydia Denworth

5 books48 followers
Lydia Denworth is a Brooklyn-based science journalist whose work is supported by the Alfred P. Sloan Foundation. A contributing writer for Scientific American and Psychology Today, she has also written for the Atlantic and the New York Times.

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170 (27%)
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Displaying 1 - 30 of 125 reviews
Profile Image for Lydia Denworth.
Author 5 books48 followers
January 18, 2020
I not only read this, I wrote it! So I am understandably biased. But upon re-reading it in preparation for publication, I've realized something important. People ask about books you read that change your life. I can say that reporting this book changed my life. It gave me permission to hang out with my friends more. I hope it will do the same for everyone else who reads it.
Profile Image for Clif Hostetler.
1,056 reviews681 followers
May 30, 2022
This book provides an interesting review of human behavior at the intersection of sociology, psychology, neurology, and physical health. There have been a variety of population studies made that consistently show a positive relationship between the number of social contacts a person has and their expected lifespan. Consequently scientists have discovered corresponding physiological markers of physical health and robustness of the immune system which also vary in positive proportion to the variety and number of social ties a person has. Simply stated, having friends is good for health.

That still leaves the question of which causes which. Maybe good health causes people to have more friends. Some examples are sited near the end of the book of improved health outcomes resulting from social programs that encourage enhanced social connections. This would seem to indicate that acquiring friends comes first, good health follows.

Of course there are differences in people's personalities with some people being highly motivated to seek friends and others who are more introverted. The book at one point offers a definition of loneliness as having fewer friends than desired. But do people always know what is best for themselves? It appears that some people who are not aware of being lonely could benefit from having more friends.

The book explores the subject of emotional stress, and how some relationships are actually toxic to good emotional health. So when reference is made to a large and varied number of relationships it needs to be remembered that measures should be taken to mitigate or control the stress caused by these sorts of encounters.

Numerous fascinating research findings studying humans, primates, and other animals are described in the various chapters of this book. They uniformly lead to the convincing conclusion that the need for relationship bonds (i.e. friendship) is hardwired into almost all species—especially in humans. The book attempts to explain the why of this inherent need by speculating on the ways during evolution of the species that friendship could have enhanced survival and reproduction. The book also explains how the body responds to friendship by describing the physical mechanisms of neurotransmitters and eye contact.

There is also some discussion in the book of whether virtual on-line interaction is as good as in-person contact. On-line social media is a new phenomenon and supporting data is limited, but the book suggests that social media is probably just another tool that can be used to enhance the maintenance of social contacts.
Profile Image for Camelia Rose.
623 reviews81 followers
January 2, 2021
This book, which centers around friendship, is part psychology and part animal study (primatology). It is well-written and easy to read.

What I've found in the book:

1. There is an evolution basis for friendship. Friendship (social bond between non-kins) does not only exist in human society. The author described several animal studies, especially primates. A study of the structure of social relationships among female baboons in Moremi, Botswana shows: 1) the strength of females’ social bonds is the most important factor in their reproductive success. 2) females who have strong and stable social bonds live longer.

2. Friendship can mean different things to different people. Number of friends may not matter much for some, but the quality does matter for all. Ambivalent relationship is not ambivalent--it is just bad.

One research says: "Men are more likely to build relationships that focus on what friends can do for them, what opportunities they can open, what kind of resources they can provide—all of which Hall describes as agency. Women, on the other hand, are more likely to expect their closest friends to offer emotional nourishment and support." Does it still stand, especially in younger generation? It sounds too stereotypical to me.

3. Chapter Four is the friendship in child development. A lot of common sense is validated by science. For example:

1) Puberty a turning point for dealing with stress, and it comes with the bad news for parents: "Up to the age of ten, mothers calmed down the amygdala by engaging prefrontal circuitry in children’s brains that works to control stress. In adolescents, who were eleven to seventeen in this study, Mom’s presence no longer worked the same magic. The brain’s response to stress remained highly reactive. On the plus side for teenagers, the necessary brain circuitry for managing the stress—a network that connects the amygdala to the prefrontal cortex—is more fully developed, so they are on their way to mature responses."

2) It is not peer-pressure, but "peer effect." “The presence of peers is so powerful during adolescence that it can make even mice misbehave,” Steinberg wrote in his 2014 book Age of Opportunity, "Pressure doesn’t have to come into it, merely presence...We came to the notion that basically when kids are around other kids it primes their reward system to be more easily aroused and more easily activated. That in turn leads them to pay undue attention to the potential rewards of a risky choice and relatively less to the potential costs.”

As my mother has told me (and her mother had told her), parents should worry about whom their kids are hanging around. Your kids' health requires them to have friends, which also means peer influence is inevitable.

4. Online friendship
Apparently various studies of social media's influence on people's mental health have produced mixed results. One researcher says:

“Using social media is essentially a tradeoff,” Hancock says. “You get very small but significant advantages for your well-being that come with very small but statistically significant costs.” What’s more, the overall effect on well-being, meaning the amount of variation among individuals that could be attributed to technology use when all effects were combined, was “essentially zero,” Hancock says. To be specific, it was 0.01 on a scale in which 0.2 is considered a small effect size.

A more nuanced questioning is needed: "The overwhelming attention to time on social media (both frequency and duration of use) ignores content or context. The very concept of screen time is essentially meaningless given the variety of possible ways to occupy that time. Who and what we interact with matter as much or more than for how long."

However, the author does not mention the highly addictive nature of these social media tools, which is a feature not a bug. In my view, this feature can only lead to worse, not better, outcome in the users' mental health and relationships.

5. The role of friendship in physical and mental health and the deficit of such can cause serious physical and mental damage.

“Human beings,” they would go on to write, “have a pervasive drive to form and maintain at least a minimum quantity of lasting, positive, and significant relationships.”

The consensus, Silk wrote, was that human friendships were “intimate, supportive, egalitarian relationships.” They required compatibility and an investment of time.

When asked, “What have you learned?”, George Vaillant, the longtime director of the Study of Adult Development at the Harvard University Health Service, replied: “That the only thing that really matters in life are your relationships to other people.”
Profile Image for Emily.
45 reviews3 followers
November 14, 2020
It was a chore to get through this book. It’s more about primates than anything, and reads like a literary review in many instances. The author spends more time introducing a researcher’s background than the research itself. And just when I thought we were getting to the meaty, human friendship-related studies (not until chapter 6, by the way), we went right back into the author’s anecdotal experience observing monkeys. I wouldn’t recommend this book to anyone who’s interested in learning more about friendship, because that I did not.
1 review
January 7, 2020
I got an early copy of the book and I already feel like it has had an impact on me. It is a great kick off book for 2020. Instead of skipping wine in January for my health, I'm having more wine and seeing friends which is far more important and fun. It is a great read filled with both great science and personal anecdotes on the importance of investing in our most basic relationships. It makes a compelling argument for doubling down on good friends. I thoroughly enjoyed it.
Profile Image for Mehrsa.
2,234 reviews3,664 followers
April 1, 2020
This is a collection of other studies about mirroring and the need to bond. Basically, our brains are geared toward social interactions. This is basic evolutionary biology covered in a lot of other books. It is useful to have a focus on just one thread (friendship), but it did not seem all that new.
Profile Image for Ari Robin McKenna.
21 reviews10 followers
February 21, 2020
Though I appreciate the wide sampling of sources collated into a single volume, "Friendship" doesn't reach for revelatory depth. The strongest theme in the book is the author's personal anecdotes about her family, which while not unrelated or forced, end up becoming central to the book, the main take-away.
Profile Image for Amber Spencer.
719 reviews1 follower
March 10, 2020
I loved a lot about this. I had a lot of friends as a teenager, but I often felt bad for wanting to be with them. I have tried not to pass that on to my kids and realize how important friends are to teenagers and this book is filled with the science to back up my feelings.
As an adult I have found some really amazing friends and the ones that want to give back to the relationship with me are the ones I still hang out with and see. Friendship goes two ways. Making time for friends and making time for our kids to have friends is important to happiness and bonding with other humans. If you think you don’t need friends, science says otherwise. Go hang out with your friends and make it a regular thing!
(Sometimes the science behind all the claims was boring to me. But maybe that was because I didn’t need much convincing.)
Profile Image for Oskars Kaulēns.
402 reviews90 followers
July 5, 2021
draudzība ir svarīgākās sociālās saites un bioloģiski noteikta nepieciešamība. lielisks pārskats par to, kā mēs kļūstam par sociāliem dzīvniekiem un kāpēc bieži vien nenovērtējam to, kas dzīves kvalitātei ir pats nozīmīgākais.
Profile Image for Leah MacFarlane.
3 reviews3 followers
January 3, 2020
I absolutely loved this fascinating book on the science of friendship. The author presents an amazing amount of information in the most readable, compelling way. It is remarkable to find out how friendship has influenced and been influenced by human evolution, and the actual biological power of the friendship bond. Denworth creates wonderful images of her global travels to meet and see in person the network of scientists who are working on this ground-breaking area. They are all so memorably drawn that what could be an overwhelming amount of information is easily absorbed and remembered. Finding out that friendships have an important role to play in the biological advantages affecting evolution was totally intriguing. I highly recommend. A perfect gift for friends on Valentine's Day!
Profile Image for Anna Walker-Roberts.
12 reviews2 followers
February 28, 2020
I’m making a film about friendship, specifically about platonic best friends, and read this book as part of my research. I loved understanding more of the science and biology behind friendship. What really hooked me initially was Lydia’s dismissal of the friendship chapter in C.S. Lewis’ book The Four Loves. I read that book and wanted to rip out the whole chapter on friendship. I immediately felt like Lydia and I would be friends :)

She does a great job of sharing the science and data while intermingling personal anecdotes that bring to mind friends of your own.
Profile Image for Alison.
10 reviews2 followers
April 2, 2020
I started reading this book days before quarantining became our collective dystopian reality. Finishing it alone in my apartment, on the heels of a falling out with a friend of nearly ten years, while feeling sick and having not left my building for (I think) four days was poignant, to say the least.

Global context aside, this was an excellent read. Denworth handles this complicated, primal, and deeply personal topic with great care and strikes just the right balance between being playful and informative. Her ability to cull information from fascinating and groundbreaking studies in neuroscience and primatology to support her central thesis--that friendship is much deeper and much more important than many, if not most, of us recognize--is impressive and makes for a compelling read.

I can't wait to hug my friends again.
Profile Image for Z. Aroosha Dehghan.
156 reviews13 followers
April 23, 2022
جالب بود
البته بعضی چیزهاش بدیهی بود
بعضی رو هم زیادی تکرار می‌کرد
ولی در مجموع خوب بود.
Profile Image for Milad.
144 reviews18 followers
February 9, 2022
کتاب مجموعه ای از مقالات و سخنرانی ها رو یکجا آورده و بررسی کرده تا اهمیت شبکه اجتماعی بزرگتر و دوستان رو نشون بده. خلاصه کتاب توی بی پلاس قبلا بهم معرفی شده بود و گوش کرده بودم. به نظرم بیشتر رو فصول اول کتاب متمرکز بود ولی علاقه مندم کرد که خود کتاب رو تهیه کنم.
نتیجه گیری کلی کتاب، طبیعتا چیزی نیست که باهاش آشن�� نباشیم: معاشرت های اجتماعی و دوستی لازمه. چیزی که برای من جالب بود، جمع آوری پژوهش های مختلف و توضیح راجع به اون ها بود. این موارد از مقاله های مختلف در رابطه با پریمات ها گرفته تا بررسی خود نویسنده در رابطه با دایره "دوستان" فیس بوکیش آورده شدن.

"بنابرین می توان نتیجه گرفت که هر چه میزان اتصال ها در شبکه اجتماعی تان بیشتر باشد، به عبارتی هرچه تور اجتماعی گسترده ترتان را در محدوده بزرگتری پهن کرده باشید، شادتر خواهید بود."
1 review1 follower
January 3, 2020
Lydia Denworth’s Friendship translates cutting-edge science in telling a compelling story that details and underscores how close connections are not only necessary - they will extend, and potentially save, our lives. She reveals and revels in a topic that is universally important and endlessly interesting.
Profile Image for Charles Nguyen.
40 reviews11 followers
February 14, 2020
I love this book as it talks about the science of friendship. Mix in a bit of monkey science with attachment, friendship in school, the deepness of connections, heredity or genetic expression, and rounding it off with the impact on our lives... woo! Much of this science is current and up-to-date. It's been a while since I've read something that triggered about 20 more books into my "to-read" list. Highly recommended for anyone who wants to think about what makes friends tick. Friendship must be one of the topics of the year as there are a couple more that I see.
46 reviews3 followers
December 18, 2019
Lydia Denworth's comprehensive look at the evolution and necessity of friendship is highly informative and engaging. I don't think I've ever devoured a nonfiction book quite this quickly, and that was all due to Denworth's writing style--she ably breaks down even complicated scientific terms and ideas so anyone can understand them by illustrating unfamiliar concepts with stories and analogies from her own life.

Learning more about what scientists are currently discovering about the importance of friendship would have been compelling enough (spoiler alert: friendship is highly important to our health and well-being at all points of our lives) but she also takes us through the all the primate studies that have been conducted through the past several decades. Interestingly, primate research teaches us that friendship is much older than humans are, suggesting that it is not just a nice thing to have; it's a biological imperative.

Denworth wraps up with an exhortation for us to pay attention to and cultivate our relationships even if we feel we're too busy for friends because just like neglecting our health, the ramifications of neglecting our friends could lead to loneliness in later life, and that loneliness has been proven to be just as deadly as any of our current health crises. Everyone should read this book and then go hug their friends and family members.
1,288 reviews3 followers
March 17, 2020
2.5 Did we really need 250+ pages to tell us the importance of friendship?
Profile Image for Alana Benjamin.
135 reviews52 followers
May 18, 2020
If you are interested in the minutiae of the human connection in our lives, this is the book for you.
It is a very wonky exploration of the effects of friendship, loneliness, and lack of connection on our overall health and by extension life fulfillment and longevity. (a relatively new area of study)

In between the many many case studies and journal articles, there are some very interesting facts and information on attachment, social connection, and bonds as we age. I was most intrigued by facts on adolescents and the importance of peer approval, social media's role in maintaining quality relationships, and the types of friendships.

The downside of this book is that it is filled with scientific studies mainly dealing with primatology and neuroscience that can be a little monotonous. I wish the book was broken up into more anecdotes and easily digestible facts and information.

Overall, it is a good read if you want to get into the weeds of the importance of friendship and connection in combatting the long term effects of loneliness.
2 reviews
January 13, 2020
I was fortunate to have read an early release of Lydia Denworth’s book—Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond. It is beautifully written and seamlessly weaves cutting edge science with the essential role of friendship. I was completely engaged by the clear explanations of the work of the scientists who have studied multiple species—from rhesus monkeys to zebra fish—to explain our interactions with certain people and what we expect and, more importantly, what we receive from those with whom we bond. I am certainly not the only one who understands how important and timely this book is. It was just selected by the Next Big Idea Club (Malcolm Gladwell, Susan Cain, Adam Grant, and Daniel Pink) as one of the six must-read nonfiction Books of Winter 2020!

For years now I have been inundated with the all the reasons why meditation improves my health. I am not knocking meditation, but as Ms. Denworth so eloquently illustrates, through clear and fascinating explanations of the neuroscience as well as personal observation, friendship is the foundation of a healthy life, well lived. After reading this book, I hugged all my friends (perhaps they were a bit bemused) and then I wanted to make new friends. My reasons were perhaps self-interested but like the monkeys and fish I knew it was essential to my well-being. I am a committed but poor meditator but, because of this book, I now know what it means to be a good friend and to have good friends. You would be well served to understand that too.

Profile Image for Melinda.
Author 1 book8 followers
March 5, 2020
But for the persistence of a close friend, the client would have died. That was the take-away from a client meeting I had a year or so ago. Like many people, the client was older, single and lived alone. Contrary to the client's normal ways, a Saturday evening dinner was canceled because the client was under the weather.



The next morning the client called in sick to teach Sunday School, and upon hearing this news the client's astute and caring friend new something was amiss and showed up at the client's door. Visibly disoriented, the client's friend knew medical attention was needed. Refusing the astute friend to call 911, the client agreed to be driven to the ER. And then the client's memory fades to black. Afterwards the ER doctor told the client "had you stayed at home one hour longer, you would be dead." Septic shock nearly killed my client. A friendship saved a life.



Today I finished reading Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond by Lydia Denworth. Her book pulled this memory from the back of my mind to the forefront. As an estate planning and probate attorney I spend my days preparing client documents related to illness and death. And I see the strain on faces when I ask who will be your health care agent? Who will be your backup? So many people have no obvious answer, and the stress is visible.



Denworth's book is heavy on the hard science behind friendship, however, it is worth pushing through if you are more of a social policy student like myself. Sprinkled throughout the book are the personal stories that bring the science to life, at least for me. From birth to retirement age (and beyond), Denworth discuss how friendships are formed, and the benefits they provide. My take-away from this book is that a power of attorney for health care is important, forming the bonds to know who to name is critical. The more "isolated" an individual feels, the greater the risk of illness. Denworth states "those who answered that they had five or fewer interactions per month with close friends and family were considered isolated". Meaning mortality risk was increased.



My only criticism of the book is that it was a bit lite on the how of friendship. She touches on the role of co-workers, faith-based organizations, community groups, and a group of friends and family. I would have enjoyed a bit more discussion, and suggestion, on how to build the critical face-to-face time into our busy lives. I can say her book influenced me. While reading this week my youngest asked for a sleepover on Friday night with 2 friends. My first thought was "no, we have a busy weekend, yada yada yada." Thinking about Denworth's discussion of her children's friends I went against my instinct and not only said "sure", but also invited a fiend of my son's to stay over as well. So our house will be filled with 5 children's voices Friday night. And when they have trouble settling down and not talking, I'll remind myself that they are forging critical friendship bonds, a lifelong need.
June 2, 2020
Poignant time during quarantine to have read this book about how social isolation is as big of a risk factor for mortality as smoking. Super interesting read overall though. How crazy is it that we think it’s crazy to realize that spending our time cultivating a deep and meaningful social network of friends is ACTUALLY medically/societally/personally valuable towards physical health and longevity? It seems obvious and yet..
Profile Image for Julie.
272 reviews2 followers
August 16, 2020
Great book with lots of research. Denworth communicated tough scientific and psychological theories, experiments, and concepts in easily relatable and graspable language. She covers the evolutionary and biological need for friendships and how and why our brains respond to friendships the way they do. I wish there had been more about the evolutionary biology of friendships and less about the impact of social media.
Profile Image for Colleen Rice.
197 reviews1 follower
September 9, 2021
Straight-forward, no nonsense science leading to what seems an obvious conclusion? Here for it. This book was packed with different studies and ways to examine friendship that were all so fascinating. Despite its scientific density, it read easily and was highly engaging. I found myself sharing aspects of new-to-me human development with Ian nearly daily, and am reimagining ways to nurture my friendships that are spread all over the country. Great read!
1,963 reviews47 followers
March 22, 2020
This is a great book on why you should have friends. I also appreciated the distinction it draws between types of personalities and friendships: solitude is when you're ok with not having / having few friends; loneliness is when you want more friends than you have. Loneliness has a detrimental effect that is comparable to trauma (e.g. poverty).

It is a book that's sympathetic to the lack of friends and the physical impact it has on people (people with close knit communities live longer). I liked the description of how humans have a social brain too - that different parts of the brain light up when making decisions.

The author also works to make this book relate-able - there's lots of anecdotes about her and her children's personal friends, though I did notice that the friendships describe seem to be same-gender friendships.
Profile Image for Tammy Strobel.
Author 7 books9 followers
March 9, 2020
FRIENDSHIP was engaging and enlightening. Denworth presented the science of friendship in a relatable way. Also, her personal stories cemented the ideas she presented in the book. Read this book and supercharge your friendships!
Profile Image for c2 cole.
92 reviews
May 20, 2020
I thought I'd be enthralled with this book as friendship is one of the topics that interests me most. And I thought it'd be a quick read since I'm reading it during the pandemic but no on both accounts. I found it grueling and had to force myself to finish it. I'm not sure exactly what was wrong with it. I felt as if Denworth included a lot of information on many studies in different areas, but not with enough depth for me to be truly interested. This was especially true in the earlier chapters on ethnobiology and neurology. Either topic is interesting on its own, but reading lists of experimenters with a few details on what they did didn't make a huge impression on me.

The later chapters which focused more on the sociology and psychology of friendship were more interesting and easier for me to read yet I can't say I came away having learned anything much really new about friendship. Looking through the notes, though, I know there are some studies and a TED talk or two I will want to follow up on to learn more about specific studies in more detail.
449 reviews5 followers
March 28, 2020
This book was MOSTLY about how humans are social animals generally, not specific to friendship. The final chapter that got into friendship didn't feel particularly revelatory, although it reminds me of what I already know--how important my friends are to me and how cultivating those friendships is not only fun, but core to my physical and mental well-being. To summary the book in two sentences, "Waldinger[, Harvard professor who oversees a long-running study of well-being,] echoed Valliant, [founding professor of the study,] in a TEDx Talk that has since accumulated nearly thirty-million views. 'The clearest message we get from this 75-year study is this: Good relationships keep us happier and healthier. Period." A good reminder at any time, but particularly this, as we find ourselves simultaneously isolated from friends and distant family and the outside world and in closer proximity than ever to our nuclear family or cluster.
Profile Image for Carman Chew.
137 reviews9 followers
December 27, 2020
For a book on friendship, most of the book ends up ironically being about Denworth's family. Unfortunately, even with her dramatic writing style, the book reads more like a lengthy lit review of somebody who's only just realised that friendship is underrated.

I'm not quite sure what kind of insight I was expecting, but maybe it would've been helpful if she interrogated her life more and built on that to expand on concepts rather than jump from concept to concept via tangential threads. For what it's worth, I think she's done some pretty extensive research, and the big names are definitely there, but it feels like every time we almost get to the core of their research, she skips on to the next "insightful point" perhaps in fear of losing the reader.
5 reviews4 followers
March 2, 2020
When I first started the book, I never expected the "bonds that bind us" to be such a contentious topic. And while I am still surprised to some extent, Lydia has definitely covered great ground on friendship, giving us an amazing survey of research to why it is needed and how we are trying to measure its impact, and also demonstrating that we are definitely not alone in being intensely social creatures (those monkeys though...)

My only disappointment, if it can even be called as such, is that apart from prosetylizing the need for friendship, it does little to point those in need in a direction that could help them gain more friendships. It would be a nice addition for sure.
This entire review has been hidden because of spoilers.
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