Visualizing evolution in action: Dynamic fitness landscapes

Fitness landscapes were invented by Sewall Wright in 1932. They map fitness, or reproductive success, of individual organisms as a function of genotype or phenotype. Organisms with higher fitness have a higher chance of reproducing, and populations therefore tend to evolve towards higher ground in the fitness landscape. Even though only two traits can be visualized this way, we can actually observe evolution in action. Building on the idea of fitness landscapes, Bjørn Østman and I decided to create some animations of simulated evolving populations to illustrate concepts of evolution that are typically difficult to comprehend.

Here we demonstrate the effect of a dynamically changing environment on an evolving population. If the environment changes slowly enough, the population can adapt and “keep up” with environmental change. But if the environment changes too quickly, evolution breaks down and the population can no longer adapt to the environment.

Warning: The GIFs on this page are large and may take some time to load.

dynamic-slow


dynamic-fast


Here’s the full video that Bjørn and I submitted to the ALife 2014 Science Visualization Competition.

Visualizing evolution in action: Density-dependence and sympatric speciation

Fitness landscapes were invented by Sewall Wright in 1932. They map fitness, or reproductive success, of individual organisms as a function of genotype or phenotype. Organisms with higher fitness have a higher chance of reproducing, and populations therefore tend to evolve towards higher ground in the fitness landscape. Even though only two traits can be visualized this way, we can actually observe evolution in action. Building on the idea of fitness landscapes, Bjørn Østman and I decided to create some animations of simulated evolving populations to illustrate concepts of evolution that are typically difficult to comprehend.

Here we demonstrate how sympatric speciation can occur when fitness depends on the density of organisms, i.e., density-dependence.

Warning: The GIFs on this page are large and may take some time to load.

static-landscape


density-dependence


Here’s the full video that Bjørn and I submitted to the ALife 2014 Science Visualization Competition.

Visualizing evolution in action: Survival of the flattest

Fitness landscapes were invented by Sewall Wright in 1932. They map fitness, or reproductive success, of individual organisms as a function of genotype or phenotype. Organisms with higher fitness have a higher chance of reproducing, and populations therefore tend to evolve towards higher ground in the fitness landscape. Even though only two traits can be visualized this way, we can actually observe evolution in action. Building on the idea of fitness landscapes, Bjørn Østman and I decided to create some animations of simulated evolving populations to illustrate concepts of evolution that are typically difficult to comprehend.

Here we demonstrate the survival of the flattest, a theory stating that when organisms experience a high enough mutation rate, the population will evolve to “flatter” fitness peaks instead of higher peaks. This theory of course flies in the face of the more traditional “survival of the fittest,” which would have us think that organisms will always adapt to the highest fitness peak. We hope to show here that there’s much more to evolution than “survival of the fittest.”

Warning: The GIF on this page is large and may take some time to load.

survival-flattest


Here’s the full video that Bjørn and I submitted to the ALife 2014 Science Visualization Competition.

It’s impossible to work your way through college nowadays, revisited with national data

Last weekend, I wrote a brief rant about how it’s far more difficult to work your way through college nowadays than 30 years ago. Some folks took it for a scientific study rather than the rant it was, and criticized it for only looking at Michigan State University’s tuition trends. In response, I decided to run a proper analysis of national public university tuition data.

With the help of some of my awesome Twitter followers, I managed to find a comprehensive data set of the in-state tuition costs for all public 4-year universities in the U.S. from 1987 through 2010. Combining that data with the Federal minimum wage trends from before, we get the chart below showing the number of hours a student would have to work on minimum wage to pay for 1 year of public university tuition in the U.S.

To save you the data wrangling, I’ll provide the data set here.

Hours worked on minimum wage to pay for 1 year of public university tuition in the U.S.

Hours worked on minimum wage to pay for 1 year of public university tuition in the U.S.

We immediately see a trend similar to before, but the data is limited between 1987 and 2010. What about the 1979 and 2013 students, as we previously looked at?

To get a better sense of the trend, I fit a linear regression to the data. According to the model, students have to work 23.7 extra hours every year to pay for tuition. If we extrapolate this trend back to 1979 and forward to 2013, we recover the same trend that I found in my previous post: The average university student in 1979 only had to work 182 hours per year (a part-time summer job) to pay for tuition, whereas the average 2013 student had to work 991 hours (a full-time job for half the year). That’s over 5x as many hours worked for the same education!

I should point out that I’m only considering tuition & fees in this analysis, and I’ve completely left out room & board, book costs, gas & car repair, and other miscellaneous expenses that build up when students are in college. Given the widespread reports that wages aren’t keeping pace with inflation, this plot would only look even more dismal if I factored those costs in as well.

Other commenters were eager to point out that I left out financial aid from this analysis. If the Federal aid trends in the past 30 years are any indication, students actually have less of their tuition costs paid for by financial aid nowadays than 30 years ago! With rising costs and lowered financial support, it’s no wonder that student debt has spiraled out of control in the past decade. The system is practically setting the modern university student up for financial failure.

In summary, I’d like folks to stop toting their college financial success stories as an excuse for the insane costs of tuition nowadays — you’re the exception, not the rule.

It’s impossible to work your way through college nowadays

Update (3/29/14): I’ve written up an analysis of national tuition cost trends in a new blog post. It turns out that Michigan State University’s tuition situation isn’t uncommon!

Earlier today, I ran across a conversation about how the cost of tuition at Michigan State University (MSU) has changed over the years. I had just finished talking with my grandpa over the phone, and he had spent the latter half of the talk extolling the virtues of working your way through college (without family support), so I was rightly annoyed on the topic already.

The creator of the discussion pointed to the historical trends for MSU’s tuition, and in another comment pointed to the Federal minimum wage trends. If you crunch some of the numbers there, you’ll get the chart below showing the number of hours a student must work on minimum wage to pay for a single credit hour at MSU. I’ll provide the data set here to save you the number crunching*.

Hours worked on minimum wage per MSU credit hour

Modern students have to work as much as 6x longer to pay for college than 30 years ago

What we see is a startling trend: Modern students have to work as much as 6x longer to pay for college than 30 years ago. Given the reports that a growing number of college students are working minimum wage jobs, this spells serious trouble for any student who hopes to work their way through college without any additional support.

Let’s crunch a few more numbers to see what a typical year would look like for a student in 1979 and 2013 working her way through college. Most students take 12 credit hours per semester and only attend Fall and Spring semester. That’s 24 credit hours per year.

The 1979 student would have to work about 10 weeks at a part-time job (~203 hours) — basically, they could pay for tuition just by working part-time over the Summer. In contrast, the 2013 student would have to work for 35 ½ weeks (~1420 hours) — over half the year — at a full-time job to pay for the same number of credit hours. If you’ve ever attended college full-time, you know that this is basically impossible.

Perhaps it’s no surprise that tuition costs are rising, and college is becoming less and less affordable by the year. Yet somehow, the idea that we can work our way through college still persists. This ethos seems to be the latest generation’s version of American Dream: If you work long and hard enough, and if you sacrifice enough, you will eventually graduate college without debt and land your dream job. But with the way this trend is going, it looks like even long and hard hours at work won’t even pay off any more.

In short, I’d like my readers to walk away knowing that it’s not nearly as easy to work your way through college as it used to be — stop telling us to do it just because you did a decade or more ago.

* Note about the data: For the minimum wage data, I set the minimum wage to the maximum for the year, even if minimum wage was raised in the later parts of the year (e.g. September). For the tuition data, I averaged the Fall and Spring tuition rates (if available), and only used the tuition rates for students admitted that year. I dropped any entries for Summer tuition on the assumption that most students do not attend Summer semester.