As I was driving north to spend a few days raking leaves at the cottage, I asked myself, "How do the trees know to change their colors and drop their leaves in the fall?" When taking botany classes over the years, I never remember any mention of the tree's brain. Like anyone seeking an answer these days, I Googled the question.
Quara.com tells me, "The process that starts the cascade of events that result in fall color is actually a growth process. In late summer or early autumn, the days begin to get shorter, and nights are longer. ... When nights reach a threshold value and are long enough, ... a corky layer of cells slowly begins to block transport of materials such a carbohydrates from the leaf to the branch. Because the starting time of the whole process is dependent on night length, fall colors appear at about the same time each year in a given location, whether temperatures are cooler or warmer than normal. ... (During this time) the production of chlorophyll slows and then stops. In a relatively short time period, the chlorophyll disappears completely." Chlorophyll is green, so the color of the leaves changes, and the leaves slowly die and fall to the ground.
Of course, all of this tells me the what and the why, but doesn't really answer my question: "How do they know?"
For me, the answer must go back to the origins of everything. Evolutionists would say this 'knowledge' came about over billions of years through the process of "natural selection." The theory of "intelligent design" holds that certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection (intelligentdesign.org). Like those who subscribe to creation, I contend that all "theories of origins" are just that - unproven theories (or observations) that are ultimately based upon (or grow from) the initial belief of the individual.
The Psalmist writes, "O Lord my God, you are very great! You are clothed with splendor and majesty, covering yourself with light as with a garment, stretching out the heavens like a tent. ... You cause grass to grow for the livestock and plants for man to cultivate. ... The trees of the Lord are watered abundantly, the cedars of Lebanon that he planted. In them the birds build their nests; the stork has her home in the fir trees. ... O Lord, how manifold are your works! ... These all look to you, to give them their food in due season. When you give it to them, they gather it up; when you open your hand, they are filled with good things. ... When you send forth your Spirit, they are created, and you renew the face of the ground ... I will sing praise to my God while I have being. ... Bless the Lord, O my soul! Praise the Lord!" (Psalm 104, selected verses)
It is none other than Jesus who is the author of life (Acts 3.15). He has created us and all things with one thought in mind - that we might live in relationship with him. Much of how he works - like the answers to many of my questions - will always remain a mystery. Ultimately it does not really matter "how they know to change their colors and drop their leaves." I am just thankful for the beauty of the season ... and, believe it or not, for the opportunity to spend a few days "raking in" the season's bounty.
What really matters is that we live in relationship with the author of life ... and how we go about doing it. But that, I believe, is wholly another topic for a different day. Although I also believe that a different application of the question "How do they know" lies beneath this conversation as well!