Anthropologists and primate researchers , but relatively recent scientific findings have disproven that notion. , and it is more sophisticated with great apes. It took a few million years after the human/chimp split for our ancestors to learn to , and that culture then spread widely in Africa. The , , and were probably all closely related and at least partly interdependent, but little seemed to change . Then the and possessed a larger brain, and new tools and behaviors are evident . The timeframes continually shrank between major events in the human journey. Only 200 thousand years later, and , and new behaviors are in evidence. Only 100 thousand years after that, anatomically modern humans appeared. Only 30 thousand years after that, about 170 kya, , probably due to necessity, where life once again was eked out on the margins, and those humans may have decorated their bodies. About 100 kya, innovation seems to have accelerated again, and by 75-60 kya there is evidence of . Needles and perhaps even arrowheads first appeared about 60 kya. There is no doubt among scientists that members of made those advances, and their artifacts provided evidence of increasing cultural and technical sophistication, which soon left Neanderthals and all other land animals far behind. About 75-70 kya, a , and there is controversy today whether that eruption was partly responsible for the that passed through not long afterward. What became today’s humanity seems to have nearly gone extinct at that bottleneck.
With the paucity of fossils, particularly between 2.5 and 1.0 mya, a timeframe in which the bones of only about 50 individuals have been found so far, discoveries are regularly announced that can be promoted as finds that will . That recently discovered better suited for tool-making, in parallel to developing humans, and perhaps is even a human ancestor, which would relegate to an extinct offshoot, not a human ancestor. With such a scanty existing record, such announcements can be more than hyperbole. There are often heated controversies over the dates of fossils and artifacts, in which changing a date can radically alter how the evidence is viewed. Many findings can change from minor curiosity to paradigm-shifting discovery and back again, depending on the dates assigned to them.
Even if we’re able to boost yields immensely by upgrading photosynthesis, this isn’t going to be a silver bullet that ends any global food crisis, present or future. It’s important to bear in mind that the hunger problem facing our world today is largely a problem of distribution, not supply. As the world population continues to grow, that may change. But any attempts to improve our crops are going to have to be coupled with policies ensuring that those extra calories are being distributed to the people who need them.
We’ve also got to face our changing climate. As the Earth warms and , many of our planet’s fertile agricultural lands are drying up, while historically parched regions are becoming wetter. We can upgrade the heck out of photosynthesis, but if we don’t have the water to grow our crops, it won’t make a drop of difference. Predicting and adapting to changing water resources is critical for our survival as a species.
Most of the photosynthesis upgrades being proposed wouldn’t be conceivable without the tremendous molecular biology advances of the past decade. Still, manipulating life in the ways I’ve described here amounts to far more than simply cutting and pasting genes from one organism into another. It’ll involve getting those genes expressed in the right place and under the right conditions, without screwing anything else up in the process. Then scientists will have to determine how these molecular tweaks scale to entire plants and fields. All of this is much easier said than done.
Eventually, the only long-term survival solution will be for humanity to move beyond Earth. Plants are going to be an , and in all likelihood, we’ll have to engineer them even further for off-world living. Upgrading photosynthesis may be a short term step toward continuing to feed humans on planet Earth, but the tools we invent along the way will help us as we venture beyond this pale blue dot.
What’s more, in scaling from molecules to fields, biologists need to consider where plants ought to be using their new photosynthesis machinery. For instance, there tends to be more red light available at the top of the canopy, compared with more infrared at the bottom. If we’re thinking about inserting different light-sensitive chlorophylls into plants, we should also be considering how to express these systems in the areas where they’ll actually be useful.
How could a crop plant be engineered to optimize the productivity of the land, instead of the individual? For one, breeders could select for certain physical traits that maximize the amount of light penetration and airflow throughout the canopy. Crops that produce more vertically-oriented leaves at the top of the canopy, for instance, will allow more sunlight to shine through to the bottom, improving the overall light availability of the system. Breeders could also select for plants that produce flowers and other non-photosynthetic structures in low-light areas, to avoid wasting the sunniest real estate.
Our culture must move in the direction of what many are already doing. I have attempted to become independent of outside energy sources. I live on one acre. The sun shines on this one acre on which I grow bushes & trees-------birds love it. These plants capture the sun's energy by photosynthesis. The plants that grow feed my goats or are burned in my insert fireplace to heat my home in winter. It requires a lot of chopping, cutting & hauling but the sun is providing the energy---not nuclear power (Diablo).
When Rubisco messes up and grabs oxygen, it sets off a reaction pathway called , which ends up burning energy and creating toxic waste products. To mitigate this problem, so-called C4 plants evolved ways of concentrating CO2 in the parts of the cell where Rubisco operates, making it harder for the enzyme to accidentally grab an O2. Algae and photosynthetic bacteria have developed other CO2-concentrating mechanisms.
The diagrams used in this chapter are only intended to provide a glimpse of the incredible complexity of structure and chemistry that takes place at the microscopic level in organisms, and people can be forgiven for doubting that it is all a miraculous accident. I doubt it, too, as . Prokaryotes do not have organelles such as mitochondria, chloroplasts, and nuclei, but even the simplest cell is a marvel of complexity. If we could shrink ourselves so that we could stand inside an average bacterium, we would be astounded at its complexity, as molecules move here and there, are brought inside the bacterium’s membrane, used to generate energy and build structures, and waste products are ejected from the organism. Cellular division would be an amazing sight.
Solar efficiency is a major aspect of photosynthesis that stands to be optimized. But catching sunlight is really just the first step. The endgame for plants is to convert that solar energy into chemical energy, otherwise known as sugar. But to build sugar, plants need a source of carbon. Fortunately, there’s plenty of that floating around in the air as carbon dioxide.