Shadows of Forgotten Ancestors by Carl Sagan

            This book is about the relationship humans and other species have with each other. Not just the kind of behavioral relationship we may have with certain species, but a DNA relationship too.  It doesn't start off right away talking about our ancestors, but instead slowly builds up to that point. It starts off slowly, giving us some background information that we may need to fully understand how species have evolved.  This book is split off into 21 sections, topics such as the earth's material, reproduction and death, the new device called "fire", specific animals, dominance and submission, what a human is, and our ancestors. At times, some sections of the book may be a bit humorous to make it more interesting to read.

            The first chapter is called "On Earth as it is in Heaven". It pretty much gives the basic facts of life - "Nothing lives forever, in Heaven as it is on Earth...They die, and they are born." (pg.11) It continues to give us more facts about how things, such as stars, were formed in space. "Stars formed in batches from huge clouds of gas and dust. A dense clump of material attracts adjacent gas and dust, grows larger and more massive, more efficiently draws matter to it, and is off on its way to stardom." (pg.12)

            In the next few chapters, it describes about life on Earth in its early years, which most species were in the water. "When life was first emerging, the Earth seems to have been mainly an ocean planet, the monotony broken, here and there, by the ramparts of large impact craters." (pg.27) Darwin's important life theories and books are also mentioned in his very own chapter. "Thereafter, Wallace always spoke of evolution as being Darwin's theory...Darwin now applied himself to the task of writing the book that would cause so much trouble. On November 24, 1859, The Origin of Species was published." Another important life factor is mentioned. "The ability of the environment to nurture and sustain large populations - the so-called carrying capacity - is of course finite. As the number of organisms increases, not all will be able to survive. There will be a stringent competition for scarce resources."

            In the 5th chapter, "Life is Just a Three-letter Word", it digs into our DNA strands and what's in it. It first starts off by showing examples of codons like: ATG AAG TCG ATC CTA . It then gives important information of being careful when reading the sequence. "With no spaces between the words, if you start reading at the wrong place, the meaning will surely change, and a lucid message might be reduced to gibberish. This is one reason the giant molecule has special code words meaning "START READING HERE" and "STOP READING HERE". (pg.77) This is where mutations are introduced. "Advantageous mutations occur so rarely that sometimes - especially in a time of swift change - it may be helpful to arrange for an increased mutation rate. Some mutator genes turn As into Gs...Some delete parts...Others accomplish a frame shift, so the genetic code is read, three nucleotides at a time, as usual, but from a starting point offset by one nucleotide..." (pg.86)

            The next few chapters describe how species have adapted to certain changes in order to be able to survive and reproduce. Habits of animals eager to find a mate are described.  In a way, it could be related to how people act when they're in love with someone. This is where our relationship with certain animals as our ancestors are hinted.  They try to become attractive to others so that they may have a chance. Or in drastic cases, where some people are really desperate for some happy time, they may become a bit wild like other animals. "When sex becomes central to reproduction, the attractiveness of each sex to the other, and the drama of choosing among rivals is moved to center stage. Associated themes include sexual jealousy; real and mock fighting; careful noting of the identities and whereabouts of potential sexual partners and rivals..." (pg.151) Although it is considered stalking if a person tries to note where his or her rivals are, it does happen a lot in this world. The things people do for love...

            In the chapter, "Lives of the Apes", it starts describing about how human behavior is similar to how they act. "...chimps get jealous. A male who rejected the solicitation of a female in estrus, but instead copulated with her daughter, was slapped in the face by the outraged mother. Cruising migrant females from the next territory are threatened or attacked by the local females - especially if the visitors go so far as to groom with one of the resident males." (pg.305) Although that kind of situation doesn't happen to humans as often as these chimps, the jealous human mother would probably do the same, if not worse. All the way to the last chapter, it starts summing up our relationship with our ancestors, especially with our similarities shared with the chimps.

            Not only does this book talk about our ancestral relationship with other animals, but it also gives us other scientific background information such as the earth material, genetic information, environmental sciences, life facts, and adaptations. Biology concepts like reproduction and death were also discussed. "How thoroughly the chimps and bonobos have erased the list of purported human distinctions! - self-awareness, language, ideas and their association, reason, trade, play, choice, courage, love and altruism, laughter, concealed ovulation, kissing,...Philosophers and scientists confidently offer up traits said to be uniquely human..." (pg.399) Most of the chapters are based on the science concepts of how chimps are very related to humans, and how there are only meager differences between us.

            Carl Sagan's book is allowing readers to understand themselves a bit further. Of course, genetic information is important to know so that we can understand what we are, but to fully understand everything, we need to know things of the past too. Finding out what we have in common with our ancestors is a huge step to discovery. This book is neatly compiled of information that brings us back to when the earth was first formed. It then goes in a semi-chronological order where the first organisms appear, and things evolve to survive. Carl Sagan's book is effecting society by letting us think about what we used to be, and this information can be used to help find other past ancestors we may have had.