# Humans are constrained by biological limits

Whether we like or not, we are all constrained by our biological limits. We have Working memory limits, we can’t imagine a five-dimensional cube, and our circadian rhythm will tell our sleep pattern. Even Usain Bolt can’t outrun a domestic cat.

# References

Ahrens, How to Take Smart Notes

Our short-term memory is also limited. We need strategies not to waste its capacity with thoughts we can better delegate to an external system. While the estimations of our long-term memory capacity are wildly diverse and rather speculative, psychologists used to tend to agree on a very specific number when it came to short-term memory: We can hold a maximum of seven things in our head at the same time, plus/minus two (Miller 1956).

Blinkist: Foer, Joshua. Moonwalking with Einstein: The Art and Science of Remembering Everything. Penguin Press, 2011.

Are you good at remembering numbers? Could you recite the numbers 12242000001012001 after reading them just once? Probably not. Most of us are only able to remember five to nine pieces of information at a time.

Blinkist: Eagleman, David. Incognito: The Secret Lives of the Brain. 2012.

The range of thoughts we can think is actually limited to things that were useful for our ancestors. For example, if you try to visualise a five-dimensional cube, you’ll find it impossible. This is because the ability to see five-dimensional objects did not provide any evolutionary advantage.

Blinkist: Walker, Matthew P. Why We Sleep: Unlocking the Power of Sleep and Dreams. First Scribner hardcover edition, Scribner, an imprint of Simon & Schuster, Inc, 2017.

Nestled deep in the folds of your brain is a primeval timepiece, an internal clock that ticks out your body’s personal circadian rhythm - a 24-hour cycle that, regardless of morning alarms and evening appointments, your body is naturally inclined to follow.