A perspective, it’s not about us humans.
Scientific theory vs. opinion.
First, something about science: there is often confusion when people read about the “theory” of evolution or the “theory” of gravity; some think it is just an idea of what these scientists have and that it is no problem to disagree with them. This is a common misconception between scientific theories and the theories we all have in our life about mundane subjects. You can have a theory of why milk was spilled on the floor or who was to blame for that car accident, but that is more an opinion you have. A scientist can have opinions, but their theories are tested by others, and till another scientist, using the scientific method1, can prove them wrong, they are treated as the truth.
Gravity is a good example. Everybody knew already that objects fall down, and over the ages, they speculated about it, and there were a lot of opinions that could not be tested yet. In the 16th century, Galilei disproved ancient believes that objects of different weights fall at different speeds. He had a thought experiment and tested it in the real world by dropping different objects simultaneously from a tower and seeing what happens. This experiment can easily be repeated, but it does not prove gravity yet; it just proved that all solid objects arrive at the ground at the same time regardless of the weight. Later, scientists calculated these forces more accurately, and they started to make predictions; they formed a hypothesis wherein they predicted the position of certain planets using their calculations. If these planets would appear at a specific place at a particular time according to the hypothesis2, you can see that as proof that their calculations are correct. Other scientists can use these same methods and see if they get the same results; this way, you can make sure no mistakes were made in the first tests. This is, in short, an example of the scientific method.
You can see now that your theory, or hypothesis, of why the milk was spilled is different from a scientific theory about gravity. The main difference is that you can never test who spilled the milk during the night; you can only assume that it was the cat. This example is not so dangerous, but if you look at medicine tested by different scientists (peer-review3) and so-called alternative medicine that is only based on the opinion that it works and so-called anecdotal evidence4, not because it is tested independently. A side note, many people, distrust so-called “big pharma” because they are In it for the money. I agree that these big companies are doing their capitalistic duty slavishly by making as much profit as possible, but so do all these alternative medicine producers. Selling snake oil is big business too.
If I now tell you that the big bang5, where our observable universe was “born,” happened 13.8 billion years ago, you have to understand that this number is the one that most scientists agree with. The simplest way I can explain what the scientist did is that they measured the speed and direction of the stars6 you see in the sky. If you calculate these directions, including acceleration and speed, you can then reverse these directions they are now going, and you will find out where every star started. It’s like filming a ball rolling on the floor and playing it backward; you will see that it ends where you pushed the ball. It turned out that all the stars also started at the same time at the same point, which was the big bang.
Start of “life.”
After the big bang, everything started to move and move. It took billions of years before our sun, a tiny star, was formed around 4.6 billion years ago. Because of gravity and its effects on everything, our sun has collected large amounts of fuel and debris that circles it. This debris starts to attract more debris, and this process slowly forms the planets in our solar system. It only took a mere hundred million years before our earth took its shape as we know it now. This debris turned rock was still an inhabitable place, but after another five hundred million years, early life was formed on planet earth. All I have written now in a few sentences is much more complex and endlessly interesting; I recommend reading about it yourself.
Scientists have tried for many years the different ways life could have started. There is some consensus but no definite answers; laboratory tests have shown that what you could call life can spontaneously appear in the atmosphere of an early planet or in hydrothermal vents in the sea. But, life did start, and one thing that life needs is a form of an archive of what that specific life form has done up to that point. This “archive” is necessary for the next lifeforms because it tells what they suppose to do, like grow a limb here and an eye there. We now call this archive DNA7, but you also have RNA8 and genes; there is much more to know about this than I can ever tell.
Calling DNA just an archive is oversimplifying it, of course, but I do it for the sake of my argument. You can find DNA from the beginning in all living things, and through natural selection, it will spread itself, and that’s how it eventually also ended in us. DNA is the one constant, and if one host disappears, it has already nestled itself in many others. Our DNA has traces of ancestors that lived millions of years ago, and through us, we carry their “knowledge” forewards. DNA is not a living being; if you could lay DNA on a table, it would not move away and start inventing things.
Suppose that life started, like I suggest, not with a plan but just because circumstances made it possible. What is then the purpose of life? We as humans have all kinds of religious and philosophical ideas about that but try to step in the shoes of the first tiny cells that popped to live in our ancient atmosphere. These cells just appeared, and they didn’t want anything; they just multiplied over and over again till they ended up like us, a thinking collection of cells and DNA. You can think of humans what you want, but they are probably the best hosts for DNA. The world will end one day with all the DNA attached to it, but these humans that are host for the “smartest” DNA are already planning to leave this planet and look for other places…for their DNA, so to say, to prosper more, far away from a swollen sun9. I guess the DNA in a kangaroo can be pretty jealous of that.
This idea of genes (DNA) having their own “plan” is not new. One of the most influential books of the 20th century, The selfish gene by Richard Dawkins, goes about this in much more detail and with even more authority than I ever can.
“Individuals are not stable things, they are fleeting. Chromosomes too are shuffled into oblivion, like hands of cards soon after they are dealt. But the cards themselves survive the shuffling. The cards are the genes. The genes are not destroyed by crossing-over, they merely change partners and march on. Of course they march on. That is their business. They are the replicators and we are their survival machines. When we have served our purpose we are cast aside. But genes are denizens of geological time: genes are forever.” Richard Dawkins, The selfish gene
- scientific method, mathematical and experimental technique employed in the sciences. More specifically, it is the technique used in the construction and testing of a scientific hypothesis. From: https://www.britannica.com/science/scientific-method See also: https://plato.stanford.edu/entries/scientific-method/
- A hypothesis is an assumption, an idea that is proposed for the sake of argument so that it can be tested to see if it might be true. From https://www.merriam-webster.com/dictionary/hypothesis#note-1
- Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work. From: https://en.wikipedia.org/wiki/Peer_review
- Anecdotal evidence is a factual claim relying only on personal observation, collected in a casual or non-systematic manner. From: https://en.wikipedia.org/wiki/Anecdotal_evidence or from: https://www.merriam-webster.com/dictionary/anecdotal%20evidence evidence in the form of stories that people tell about what has happened to them.
- The Big Bang Theory is the leading explanation about how the universe began. At its simplest, it says the universe as we know it started with an infinitely hot, infinitely dense singularity, then inflated — first at unimaginable speed, and then at a more measurable rate — over the next 13.8 billion years to the cosmos that we know today. From: https://www.space.com/25126-big-bang-theory.html
- In 1929 Hubble published his first paper on the relationship between redshift and distance. He tentatively concluded that there is a linear redshift-distance relationship; that is, if one galaxy is twice as far away as another, its redshift is twice as large. Two years later Hubble and Humason presented what astronomers and cosmologists widely judged to be very convincing evidence that the relationship is indeed linear and hence that a galaxy’s redshift is directly proportional to its distance. From: https://www.britannica.com/biography/Edwin-Hubble see also: Hubble provided evidence that the recessional velocity of a galaxy increases with its distance from the Earth, a property now known as “Hubble’s law”, despite the fact that it had been both proposed and demonstrated observationally two years earlier by Georges Lemaître. The Hubble–Lemaître law implies that the universe is expanding. From: https://en.wikipedia.org/wiki/Edwin_Hubble
- DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA)… From: https://medlineplus.gov/genetics/understanding/basics/dna/ and: The chemical DNA was first discovered in 1869, but its role in genetic inheritance was not demonstrated until 1943. In 1953 James Watson and Francis Crick, aided by the work of biophysicists Rosalind Franklin and Maurice Wilkins, determined that the structure of DNA is a double-helix polymer, a spiral consisting of two DNA strands wound around each other. The breakthrough led to significant advances in scientists’ understanding of DNA replication and hereditary control of cellular activities. From: https://www.britannica.com/science/DNA
- Ribonucleic acid (RNA) is a molecule similar to DNA. Unlike DNA, RNA is single-stranded. From: https://www.genome.gov/genetics-glossary/RNA-Ribonucleic-Acid and: All living things reproduce, copying their genetic material and passing it on to their offspring. Thus, the ability to copy the molecules that encode genetic information is a key step in the origin of life — without it, life could not exist. This ability probably first evolved in the form of an RNA self-replicator — an RNA molecule that could copy itself. From: https://evolution.berkeley.edu/evolibrary/article/side_0_0/origsoflife_04
- The most probable fate of the planet is absorption by the Sun in about 7.5 billion years, after the star has entered the red giant phase and expanded beyond the planet’s current orbit. From: https://en.wikipedia.org/wiki/Future_of_Earth