# What advantage does white bark provide for a birch tree? **URL:** \ **Category:** Factual Questions\ **Created:** [January 2, 2022, 3:12pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084 "2022-01-02T15:12:27Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [January 2, 2022, 3:12pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084/1 "2022-01-02T15:12:28Z")
Thinking about evolution and the features that lead to continuation of species, and wondering about the whiteness of a birch tree. I think it must confer some type of advantage to the organism or it wouldn’t have survived to this point. Is there a generally accepted explanation of this aspect of this plant? Does whiteness provide some degree of protection from predatory insects, etc.? Curious. ---
**Author:** ![solost](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/solost/32/11776_2.png) [@solost](https://boards.straightdope.com/u/solost)\ **Post date:** [January 2, 2022, 3:22pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084/2 "2022-01-02T15:22:00Z")
This question interested me, so I googled “why is birch bark white” and here is the #1 hit: [Why are Paper Birches so White? | Autumn 2010 | Articles | W](https://northernwoodlands.org/articles/article/why-are-paper-birches-so-white). Tl;dr: the whiteness of paper birches as an evolutionary adaptation is thought to be in order to prevent the cells of the dormant trees from suffering too much temperature fluctuations during sunny winter days. This gives birch trees an advantage in northern climates. ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [January 2, 2022, 3:22pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084/3 "2022-01-02T15:22:31Z")
Seems to be because birch trees are widespread in higher latitudes (polar and subpolar), where dark bark would lead to high temperature differentials between those sides exposed to the Sun and the other sides. [Why are Paper Birches so White? | Autumn 2010 | Articles | W](https://northernwoodlands.org/articles/article/why-are-paper-birches-so-white) ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [January 2, 2022, 3:44pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084/4 "2022-01-02T15:44:34Z")
I suppose that’s the best of the current hypotheses. Of course, one has to wonder why other trees with darker bark that also grow quite far north and encounter wide temperature swings also don’t suffer from the same problems. Maybe it’s the combination of the lighter color and the thinness of the bark. Thanks. ---
**Author:** ![Stana\_Claus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stana_claus/32/13874_2.png) [@Stana\_Claus](https://boards.straightdope.com/u/Stana_Claus)\ **Post date:** [January 2, 2022, 4:31pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084/5 "2022-01-02T16:31:47Z")
Mutations that are passed on genetically don’t necessarily create an actual advantage for the species. As long as they don’t create a disadvantage that prevent individuals from reproducing, those mutations will continue to be passed along to future generations, advantageous or not. White bark on birch trees may not be particularly advantageous, but is certainly not a disadvantage to any significant degree. ---
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [January 2, 2022, 5:20pm UTC](https://boards.straightdope.com/t/what-advantage-does-white-bark-provide-for-a-birch-tree/957084/6 "2022-01-02T17:20:20Z")
I agree with **Stana\_Claus** that not every trait has to be adaptive. For a further treatment of this idea, see ‘spandrel’: > **[Spandrel (biology)](https://en.wikipedia.org/wiki/Spandrel_(biology))** > > Pages for logged out editors learn more > > In evolutionary biology, a spandrel is a phenotypic trait that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection. Stephen Jay Gould and Richard Lewontin brought the term into biology in their 1979 paper "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme". Adaptationism is a point of view that sees most organismal traits as adaptive produ...