Wednesday, February 21, 2018

Solitary Diner is Famous!

I'm featured in a guest post today at Chief Mom Officer.  Head over and take a look!

And if you've found my site through CMO, welcome.  Leave me a comment so I know who you are.

Saturday, February 17, 2018

Trading Money for Happiness

Like any good HSP, I don't like to be too busy.  Long to-do lists and piles of unfinished work make me anxious.  Extended periods on call break me a little mentally.  I'm not entirely sure how I survived residency, in retrospect.

As an attending, my happiness is affected a lot by the call schedule.  When the 2018 call schedule came out last year, I was initially ecstatic:  no less than a month between blocks of call*, all of my requested days off, and Christmas off for the second year in a row.  I was a tiny bit disappointed to see that I was working a lot of the long weekends, but that was a small sacrifice for what was otherwise pretty much the best call schedule I could ask for.

And then a revision came out.  And suddenly I was doing two extra weeks of call, with only a two-week break before I had to do my next stretch of call.  And the second stretch of call was immediately before my trip to France, meaning that I would be going into vacation tired and inevitably behind at work.

I was not happy.  I angrily** emailed the person in charge of making the call schedule to try to get it changed, but she had clearly had enough of dealing with demanding physicians, and she told me that I would have to find someone to switch with myself.  She was done.

So I studied the call schedule, looking for someone with whom I could switch one of my dreaded call periods.  There were a few options that would make things better, but all of them had at least one drawback:  during my beloved theatre festival, right before a major presentation, too close to another call period.  No matter how I switched them, the two extra weeks were going to make some stretch of my year miserable.

And then it occurred to me that I could just get rid of them.  Call is as lucrative as it is unpleasant, and there are other physicians who value money more than I do.  A few quick emails, and two weeks of call were gone.

The moment I got the email confirming that someone else was taking my call, I felt light.  I hadn't even realized how stressed I was feeling about my schedule until suddenly it was reasonable again.  I felt the tiniest bit of regret about the money I would lose out on, because I still have a line of credit to pay off and retirement savings to build, but it was tiny.  So tiny.

Having just come off a two-week stretch of call, I am currently even happier than I was initially about my decision to give up the extra weeks.  Even though I like the inpatient work that I do, I have spent the past two weeks counting down the days (and sometimes hours) until I would be able to turn off my pager.  I have hated the constant anxiety that comes from not knowing when I would get paged or what new challenge I would have to deal with next.  I need my downtime to be happy and healthy, and two weeks with none of it is hard.

This is what financial freedom means to me.  The ability to say "This is not worth the money" and walk away from something that makes me miserable.  Two weeks with no call is sweeter than any big house or fancy car will ever be.

*We do 1-2 weeks of call at a time for a total of about 10 weeks per year.

**Not really.  I am not an angry person.  At worst I am slightly passive-aggressive, and even then I'm mostly passive.

Sunday, February 11, 2018

When Money Meets Dating

When my ex and I broke up, I gave myself a six-month hiatus from dating.  I wanted to relearn how to be happy as a single person before I started dating again, in the hope that I wouldn't make bad relationship decisions to avoid being alone.

It ended up being easier than I had expected.  I had been unhappy in my old relationship for a long time, so the absence of the relationship's negativity in itself felt like happiness.  And there are big positives to being alone.  I like planning trips to France without considering what someone else wants to do, and I like always getting to pick the movie. 

Then my ex started dating again, and I got jealous.  I was doing so well with being single that I decided I didn't need to wait a full six months, so I signed up for an online dating site about a week ago.  It has been about as much fun as I expected it to be, with my previously healthy self esteem now as volatile as the stock market.  I check my profile more frequently than Twitter, and I devote way too much of my precious mental energy to the eternal question of "Why didn't she respond to my message?"

A friend of mine who is in a happily committed relationship keeps telling me that I should enjoy the process, which makes me kind of hate her.  Meeting new people is anathema to an introvert, and it is only made worse by the inherent vulnerability of trying to find someone who will like you enough to want to share your bacteria.  The best I can do so far is view this as a means to an end, and if I survive the process without hating it*, I will consider myself to have handled it well.

When I first subjected myself to this hell five years ago, I didn't really think about money.  I was a solid five figures in debt, so I didn't worry that someone was going to pursue me for my wealth.  But now, things are...different.  I'm on pretty solid financial ground for a forty-year-old, and assuming the stock market stops imploding, my finances are going to keep getting better very quickly.  My financial situation removes a lot of ordinary worries from my life, and it also lets me do a lot of things that most people can't.

One of the first things I've noticed with online dating is how different my travel history is from most people's.  "Where have you traveled?" is a common conversation starter online, and I feel uncomfortable listing off all the places I've been lucky enough to visit.  I abhor bragging, and it feels like that's what I'm doing when I say "Oh, I've traveled to all the places you have, but also 20 other places, because I am a rich doctor."  (I'm not actually that awkward online.  Hopefully.)  I know that this is a really nice problem to have, and this is not a complaint but rather a reflection, but it is still weird to me.

The bigger issue that arises with online dating is financial compatibility.  My city has a pretty shallow lesbian dating pool, so picking a partner isn't like customizing a sandwich at Subway.  What if I find someone who is cute and funny and nerdy but is terrible with money?  Or who wants to stay at home and play with the cats while I pay all the bills?  (Note to the internet:  If you are a queer woman who would like to pay all the bills while I stay home and play with the cats, my email address is on the sidebar.)

Dating is so frustratingly difficult. 

*I was going to make a joke about being murdered, but have you heard about the horrible murders in Toronto's LGBTQ* community

Thursday, February 8, 2018

Grief is Not Linear

When I was in my third year of medical school, my Dad asked me to feel a lump in his armpit.  Seven months later, he died of the melanoma that had metastasized from a tiny mole on his arm.

Surviving my Dad's death was one of the hardest things I've ever done.  I wrote about it here once, in the part of the blog that was lost in the great purge, and I described it as being like walking around without skin.  Everything hurt.  I made it through my last two years of medical school only thanks to some very supportive friends and terror at the thought of not matching to a residency program.

And then my Dad was gone and medical school was over, and I thought that I had left grief behind.  I didn't think of him often; I could talk to patients about death without crying; and I started to feel happy again.  (Or, as happy as a neurotic first-year Internal Medicine resident is capable of feeling.)  I was moving on, and grief wasn't coming with me.

Until it did.  When I matched to fellowship, I grieved the fact that my father would never know what specialty I had gone into.  When I started dating my first girlfriend, I grieved the fact that he would never see me dating a woman, even though he'd reached a tenuous peace with me being bisexual.  And then again, in the middle of my last and longest relationship, I grieved that my girlfriend would never get see firsthand how much I am a clone of my father.

I have been surprised over the past eight years to realize that grief never goes away.  It lies dormant for a while, sometimes long enough that I can forget it was ever there, but it inevitably returns, each time just as painful as when it was fresh.  Every time it comes back feels like a surprise hit to the chest, knocking the breath from my body.

The same thing is happening right now with the semi-recent end of my relationship.  A few weeks ago, I found myself humming happily at work, and I distinctly remember thinking about how nice it was to be so happy.  I was even going to write a smug blog post about how good life was and how bloody happy I was, but I was enjoying my happiness too much to bother.

And then my ex-girlfriend started dating again.

And posted pictures of her new girlfriend on Facebook.

And now I feel like I'm 14 instead of 40, because I am hurting over my ex-girlfriend's social media activities.  I am supposed to be over her, and yet I find myself barely able to drag myself through the day.  I cry on my drive into work, because I have to pass the coffee shop where we waited while we got winter tires, followed by the restaurant to which we took her friends from Egypt to try schnitzel.  Grief redux.

And it is completely irrational, because there is no part of me that wants to go back to the relationship.  It's not even that I want her to not date, because I do want her to date and to be happy.  I'm not a horrible person wishing misery on her just so that I won't be miserable.  And yet, I am sad.  Horribly, inexplicably, unexpectedly sad.

And I can't even drink, because I'm still on call for eight more days.

Friday, February 2, 2018

How Do We Talk About Money When We're Rich?

I've noticed something interesting about language in the personal finance community.  A lot of the bloggers who have been financially successful have gotten there as a result of being some degree of frugal (from Frugalwoods extreme to Physician on Fire more relative frugality), and as result, even when people have a lot of money, they don't necessarily think of themselves as being rich.  Instead, the term "financially independent" is often used to describe net worths that many people would consider enough to make someone "rich".

Does it matter?  Is there any difference between describing yourself as financially independent versus rich?

From a totally self-absorbed perspective, I think it does.  Even though I am way far away from the net worth of Physician on Fire, I have recently started thinking of myself as rich.  I am earning six times the median household income for my city, I'm increasing my net worth at a delightfully high rate, and I can afford to buy pretty much anything that I could possibly want.  I am very financially lucky, and I will hopefully continue to be this lucky until I retire at some to-be-determined date in the future.  This, to a person who spent all of her life until recently at the lower end of the middle class, is rich. 

And for me, there's value in calling myself rich.  It helps me control my financial anxiety by reminding myself that I am actually doing really well, even though the part of me that craves security always wants my net worth to be higher.  It reminds me to be grateful for what I have, because this level of earning and financial security is not ordinary.  It also makes me mindful to not be a jerk to my friends who are not as financially well off, and to invite them over for dinner instead of out to eat at an expensive restaurant.

Personally, I also believe that being rich carries with it some obligations to society.  People who are rich have a disproportionate amount of power in society, and I believe we are morally obligated to use some of that power to help shift society towards greater equity.  That might mean voting for progressive tax laws that favour lower income earners, even if it costs you directly (i.e. doing the exact opposite of what the POS Republican tax bill just did).  Maybe it's advocating for a $15 minimum wage so that people who work full-time can at least come close to supporting themselves and their families with a single job.  Maybe it's giving some of your wealth to charities that help marginalized people and strengthen the communities they live in.

When we don't call ourselves rich, it's easy to ignore these obligations.  It's easy for someone with a $2 million net worth to say "I'm just an ordinary guy trying to live frugally" while leaving a shitty tip for his underpaid server.  But if we acknowledge our own wealth, it at least gets us closer to recognizing that the server needs (and deserves) that money a lot more than we do.  And maybe acknowledging our own abundance makes us a little bit more likely to share it with others.

Thoughts?

Friday, January 19, 2018

Making Weekends Work Better

When M and I were together, I didn't have a lot of control over my weekends.  She loves weekends with a passion even greater than my love of all things nerdy, and she would wake up by 7 am on Saturday ready to go.  I refused to get up any earlier than 9 or 10 am, depending on how exhausted I was from the week, but as soon as I was out of bed, I was at her mercy.  Weekends would be a flurry of constant socializing/eating out/entertainment, and by the end of each one, I would be as tired as I was at the beginning.

The first few weekends after our breakup were pure bliss.  I slept in as late as I wanted, lounged in front of my computer for hours, and relaxed in a way that I hadn't for years.  Not only was I unwinding from the stress of a relationship in its death throws, but I was also recovering from years of being busier than I would choose to be.  I loved it.

But...after a few weeks...I got bored.  I got used to being well-rested, and I no longer needed to spend 12 hours in a day binge watching Stranger Things while eating food from Skip the Dishes.  I found myself actually longing to spend time with other people and to do some of the activities that had previously left me feeling overwhelmed.  So in the past few months, I've been experimenting with my weekends to figure out what works best for me.  In honour of this being the beginning of the weekend, I give you some of my thoughts on how I currently plan a good weekend.

Planning social events in advance:  None of my friends are flexible.  Most of them are physicians or work similarly demanding jobs, and many of them have children, so making plans with them requires effort and time.  Where I used to always have my girlfriend to spend time with, in the past few months I've had to get used to depending on others for human interaction, which requires booking things days to weeks ahead.

Making a schedule:  If left to my own devices, I will waste time for hours (hello Twitter) before emerging from my internet fog to discover that I've accomplished nothing.  Which is not a good thing, because weekends are my time for all of the shopping/cleaning/laundry/cooking that keep me going through the week.  I feel kind of pathetic every time I do it, but for weeks now, I have been writing a schedule for my weekend, and it really helps.

I tend to write two schedules:  one of the things that I must do (social events, essential life maintenance) and one of the things that I could do if feel motivated.  This way I can adjust my activities to my energy level and to what I feel like doing at any given time.  While still making sure that I have clean underwear for Monday.

Flexible events:  As an introvert, I have a very fine line between "Wow, I'm having so much fun at this social activity" and "Dear God, please don't make me ever have to interact with another human being ever again".  Unfortunately, I can't always predict where that line will be, so some weekends three social events will be the perfect number, whereas other weekends I will be hiding under the table by halfway through the second.  Enter the flexible social events.  Things that I can do if I'm feeling bored/lonely, but that I can also back out of if I want to.

Tonight, for example, there is a movie night at the school where I take my French lessons.  It's in my calendar, and it's something I'd like to do, but it's also something I can back out of with no warning if an evening on the couch with my cats is more to my liking.  On Sundays, I also have a conversational French group, which again, I can choose not to go to if I'm suddenly feeling too socially awkward to try to conjugate verbs dans le conditionnel with people I barely know.

Meetup.com has really been great for this, as there are all kinds of events going on in my city, and most of them can be planned and/or cancelled last minute.  I've mostly just done French activities so far, but there are also knitting groups and book clubs that I'm thinking of joining.

(Is there an aware for being the most cat ladyish of all the middle-aged cat ladies?  Because I JUST WON IT.)

Exercise:  The bane of my existence, but also something that is necessary and that makes me feel better.  I have done this for a grand total of one week, but I am trying to do something physical every Saturday and Sunday.  There is a gym two floors down from my apartment, and I live on a running/walking path, so I have absolutely no excuse not to.

So that's how I'm currently doing weekends.  This weekend I'm about to head out to my French movie; tomorrow I have a very informal brunch with friends and dinner/movie with other friends; and Sunday I'm meeting my conversational group.  For "must do" things, I am getting my passport application sent in, making granola, cleaning, and doing laundry.  And for potential fun things/could do things, there's a new episode of Top Chef online, I have a pile of stuff to take to the thrift store, and there are always books.  Glorious, glorious books.

I should probably also call my mother.

I realize as I write this that I am immensely lucky to have such a flexible weekend.  I'm sure there are some working parents out there who would be happy if their weekend includes peeing in private once and getting most of their children to wear pants most of the time, and for them my weekend might seem ridiculously leisurely.  But this is entirely by design!  I spent years of my life living in survival mode as a medical student and resident who never had enough time.  Now that I have some extra hours to spare, it's time to enjoy it.

What do you have planned for the weekend?

Tuesday, January 16, 2018

Life as a Highly Sensitive Physician - Part One

A little over a year ago, I stumbled across an article about highly sensitive people.  I had never heard the term before, but as I read the article, it resonated very strongly.

Feel more deeply?
Emotionally reactive?
Take longer to make decisions?
Detail oriented?
Cry more easily?

That's me!  After reading the article, I went on to do a self quiz, and the answer that came back was basically "You fit this profile so perfectly, why did you even need to take the quiz?"

So yeah.  I'm a highly sensitive person.  Meaning that I tend to respond very emotionally to things, that I am very sensitive to criticism, and that I can get overwhelmed easily.  These were all things that I knew before reading the article (and the subsequent articles/blogs/books on the subject that I have read), but the concept of a highly sensitive person was helpful to me for the way that it presented my individual traits as something bigger, some complete personality type that described me shockingly well.

It also helped me by explaining why some aspects of work were much harder for me than for other people.  All through medical training (and into my first years of practice), I would look at the high achievers around me and wonder how it was that they were able to accomplish so much more than I did.  How could they work a long day and then come home and raise a family and do research projects?  And without hating their lives? 

Identifying myself as an HSP has helped me to realize that things exhaust me more than they do other people.  I engage deeply with everything I do, and so I use up a lot of energy doing my work.  One challenging conversation can deplete a lot of my emotional reserves, so when I have a day with multiple tough patients, it isn't surprising that I have no energy for anything else in the evening.  I'm simply done.

This happened to me last week, when I had to tell a long-term patient that he was dying.  That interaction was difficult enough, but then it was followed by a number of really tough disclosures about personal trauma from other patients.  I did everything I could to be present for my patients and to help them get the resources they needed, but by the end of the day I had nothing left.  I spent my evening on my couch binge-watching Top Chef and eating leftovers from the fridge, physically and mentally unable to do anything else.

When I tell stories like this to some of my colleagues, they look at me like I'm crazy.  It's not that they're not empathetic or that they don't care about their patients*, it's just that they don't personalize things in the way that I do.  They can detach from their patients and move on quickly, whereas I struggle to not be too deeply affected by my patients' stories.

But it's something I'm working on.  I have zero desire to burn out early, so I'm constantly looking for ways to do my work well without giving so much of myself.

Which will be a subject for a future post, because for the moment it's time to read a book and recharge for work tomorrow.

*Well....for some of them it is.

Friday, January 12, 2018

Do I Need to Make Resolutions?

Since the end of 2017, I've been thinking a lot about writing a resolutions post.  I've been reading everyone else's posts, in which they talk about their goals of saving X dollars or losing Y pounds, and I've been thinking I should do that too.  But as I read these posts and think about writing my own, I find myself paralyzed by the fact that I have no idea what to resolve.

My challenge with resolutions is twofold.  First, I am not a person to make a resolution for the sake of doing so.  If I commit to doing something, it has to be because I believe that doing so is going to make me happier or is somehow going to make me a better person/make the world a better place.  Second, I am really, really bad at keeping resolutions.  Like my recurrent resolution to exercise.  A look at my last post about exercise shows that it starts with a paragraph bemoaning my failures:

"Oh exercise, how I struggle with you.  With just a quick look through the blog, it's easy to find multiple posts in which I'm either committing to exercising more or lamenting the fact that I've failed at exercising more (see here, here, here, here, and here for just a few examples).  It's not a habit that comes easily to me."

I worry that committing to anything, especially exercise, will inevitably lead to me writing a follow up post in a month or two talking about how miserably I've failed at my commitment.  Which makes me ask the question, why do I feel like I need to write a resolution post?

While part of this feeling is just the feeling that I should be doing what everyone else is doing, I think another part of it is a desire to create some sort of...shape in my life.  I feel like I'm in a phase in life in which I go to work, pay off debt, save for retirement, learn a few more words of French, and keep repeating ad nauseam.  I'm 7-10 years away from hitting FIRE, and I will likely keep working even when I reach FIRE, so this is not going to be a short phase.  There is an incredible monotony to this stage, and I wonder if I could somehow break up the monotony with a resolution.  2018 will be the year that I become a true minimalist/ban all shopping/run a marathon...something other than just the year in which I keep going to work every day and slowly trudge forward with life.

Hmmm.  This post is turning out much darker than I had expected.  Maybe because I'm alone on a Friday night and it's -26C outside and I drank a glass of Malbec before I started writing?  Maybe because I got word that a longtime patient of mine died yesterday, and I can't quite believe that he's gone, so the sadness that I haven't yet allowed myself to feel is coming out in other ways?

There is part of me that is longing desperately for a solution to this.  To be able to say that I am going to do X in 2018 and everything is going to be perfect.  But maybe life doesn't work that way.  Maybe it's harder than we all like to pretend it is, and we can't solve everything with a resolutions post.

Sunday, January 7, 2018

How I Like to Travel

The first time I ever traveled overseas, I was 22 years old, and I had just graduated from university.  Using my parents' travel miles, I flew to Europe with my good friend N, whom I'd known since I was five.  We had six weeks, ridiculously heavy backpacks, Eurail passes, and very little money.  It was going to be amazing.

Except, it kind of wasn't.  I mean...there were moments that were amazing.  Like the first day in London, when I walked around the city with my mouth hanging open saying things like "OMG...Alfred Russel Wallace lived here*.  OMG...MAHATMA GANDHI LIVED HERE!!!"  Or the beautiful day we spent on a boat on Loch Ness, before I discovered how badly I had burned my legs because I had decided to "let them tan".   But there was also a lot of hard stuff.


The biggest problem was that N and I wanted to have completely different trips.  I had planned for the trip obsessively, reading Let's Go Europe from cover to cover and marking things as "Must-See" or "Would-Like-To-See-If-We-Have-Time".  I had practiced saying Hello/Goodbye/Please/Thank You/I desperately need a bathroom now in the languages of every country we would visit.  And I had dreamed of all the nerdy historical places we would visit:  Westminster Abbey, Edinburgh Castle, Notre Dame Cathedral, the Roman Forum. 


N had packed her party clothes.  Unbeknownst to me, this trip for her represented an opportunity to escape from her somewhat overprotective parents and just have fun.  She had almost no desire to buy the discount passes that let you see all the historical sites in a city, but every desire to meet people at hostels and go dancing.  So for six weeks, we cramped each other's style, arguing constantly about whether to spend our time in a museum or a bar.  By the time we flew home, we were barely talking to each other.

I realized on that trip that I have some pretty specific desires when I travel, and they aren't necessarily the desires of others.  Which is completely okay.  I in no way judge the crazy people who want to be social and spend times in crowded spaces.  I simply don't want to travel with them.

Over the years, I have been very fortunate to have lots of opportunities to travel.  And with each trip, I've gotten even better at knowing what I will or will not enjoy.  Which is particularly relevant to me right now, as I just bought tickets for a conference and vacation in France this Spring.  FRANCE!  If you follow me on Twitter, you will know that I have been posting there frequently about my excitement about learning to speak French and planning my trip.  And to build on that excitement, I've decided to post about some of the things that make a great trip for me.

Really Nerdy Activities:
I love nerdy things, and the more I embrace this fact, the happier I become.  When traveling, I have no interest at all in the popular shopping district, but I absolutely do want to see the collection of 18th century dioramas/the site where a famous scientist was born/Galileo's middle finger.


When traveling, I seek out the oddities.  I look on Atlas Obscura to find places to visit (Oradour-Sur-Glane is high on my list for France).  I allocate entire days to medical and natural history museums.  And I love every minute of it.




Traveling Alone:
Shockingly there are few people in this world who want to spend hours with me in a natural history museum photographing a dodo bird (A DODO BIRD!) from every angle.  When I travel with another person, it is inevitable that at some point the other person will become impatient and/or I will feel rushed.  Which is quite easily overcome by me simply traveling alone.

While traveling with someone else isn't entirely negative (eating in restaurants tends to be better with another person), I do tend to prefer traveling on my own.  I like having complete control over where I go and what I see.  I like being able to commit a day of travel and four hours on a bus to visiting the seaside town from which the French explorers departed for Canada.  And I like never being dragged out in the evening to socialize with people I don't know.

Flexible Schedule:
Whenever I travel, I tend to alternate between days of "OMG I'm so excitied!  I'm going to see three museums and take a walking tour and take hundreds of photos!" and days of "Cobblestone hurts my feet and I don't like the food here and I want to stay in bed and Internet".  This pattern repeats itself on every trip I go on, and if I ignore my need for downtime and try to push on with the sightseeing, I will inevitably become miserable.  I've learned to build flexibility and extra time into my schedule so that, when needed, I can spend a day on the couch with a block of cheese and a good book and recharge my traveling energy.

Small Cities and Towns:
When N and I went to Europe, we gave ourselves four full days in Rome, recognizing that there was a lot to see.  And for four days we rode on the crowded subways and got catcalled by Roman men and saw site after site of broken columns.  For me, I was overwhelmed by the number of people and by the sense that no matter how much we rushed, we would never see everything.  I learned from my visit to Rome that I prefer the small places to the big.  Small places may not have as many things to see, but I enjoy the sense of being able to see everything, even when I go at a leisurely pace.  And I love the oddities that turn up in small places, which would never attract tourists in a big city, like the preserved two-headed pig in the farming town where my grandparents lived.

Packing Light:
On my first trip, I bought the biggest backpack I could find, and I filled it with everything that would fit in it.  And then I packed a second smaller backpack as a day pack.  Even though I was only 22 years old, I felt like an old woman thanks to the constant back and shoulder pain from carrying my things around.  When I watched the movie Wild, I couldn't stop laughing in recognition at Cheryl Strayed's pack (although, for the record, I did not pack 12 condoms for my trip to Europe).


Every time I travel, my suitcase gets lighter.  I simply don't need much stuff, and I hate hauling a heavy bag into airport bathrooms and onto trains.  On my most recent trip, which was to Quebec City, I took only my camera bag and a carry-on suitcase, and it was still more stuff than I needed.  I will probably need to take a larger bag to France, as I need to bring work-appropriate clothes with me, but you can bet that it will be packed as lightly as possible.  (Leaving room to bring home wine.)

So this is how I travel.  A solitary introvert with a tiny bag and a big camera, visiting the nerdiest places I can find.  My idea of a fun vacation would probably be a nightmare to a more outgoing person, but it works perfectly for me.  Which I think is a good guiding principle for life:  do what works perfectly for you.

*You know you're a nerd when you not only know who Alfred Russel Wallace was but also still feel angry that he didn't get the recognition he deserved for the theory of evolution.