April 5, 1986.
Hill Valley.
Marty rode his hover-board up to Doc's house and found his friend was in the garage and appeared to be installing something into the Delorean.
"Hey, Doc! What's up?" Marty said as he stepped up to him inside the garage.
"Hello, Marty, I'm just installing a new flux capacitor for our time machine here," replied Doc. "What's up with you?"
"Well, I just got this new assignment for Biology class," Marty said with a rather defeated sigh.
"Well, what is it about it that has you feeling defeated?" inquired Doc as he knew Marty well enough to know when something was troubling him.
"It's about this thing called evolution," Marty said. "We're studying evolution this year for this semester."
"Well, that is certainly a good thing," Doc said approvingly. "I can remember back when I was your age evolution was not allowed to be taught in schools at all. So it seems now the human race is evolving to a better understanding."
"And that is the thing, Doc," Marty continued with frustration. "I don't understand this evolution thing, and my Biology professor Mr. Dinklidge wants us to write an essay about how we believe the human race has evolved, that is how we've changed, as a species, and also how we've stayed the same. He explained to us how we evolved from apelike beings called Australopithecus Afarensis. I just can't really fathom my ancestors as being monkeys."
"That is probably because your ancestors weren't actually monkeys, but were still humans. Just with much more monkey-like qualities and appearances," Doc explained calmly to Marty.
"That does sound more fathomable," said Marty. "But I still can't really picture it as it's just too hard to think back that far into the past."
"I can understand that," Doc said understandingly. "And I myself had been curious lately to see how far it is possible to travel into the past and so I took out the flux capacitor and made some technical adjustments and renovations to it and then I reinstalled it into the Delorean and now we will have the ability to travel back to the time of the Australopithecus Afarensis. I also made it so that it can travel to different places as well as times so we can go back to where our ancestors originated which was in Africa. We may even get to meet Lucy. Have you heard of her?"
"Yes, I think so," said Marty. "Mr. Dinklidge showed us a picture of the bones of her which archaeologists found in Ethiopia twelve years ago and named her Lucy after the Beatles song Lucy in the Sky."
"That is correct, Marty," said Doc. "And I know there has since been some debate over whether or not Lucy really is an ancestor to us but I personally think she is." He then went around to the other side of the Delorean and opened the door for Marty. "Hop in," he said.
So Marty did and fastened his seat belt just as Doc got in on the other side and did the same.
"Brace yourself for temporal displacement," Doc said seriously. "And maybe something else," he added, "because I have a feeling we may find ourselves in a different atmosphere of practically a different planet."
Then Doc started the Delorean, drove it out of the garage and they took to the air as he sped it up until it reached eighty-eight miles and then they disappeared through the time portal created by it.
Ethiopia, 2.7 million years ago.
They reappeared in a sky that was a completely different shade of blue and was as clear as could be and a sun that seemed to somehow shine much brighter than it did in their time. They looked down and saw what appeared to be a vast jungle filled with trees that looked completely different from the ones they were used to seeing.
"Wow, Doc!" gasped Marty. "We really are practically on a different planet here!"
"The sun looks so much brighter because it is so much younger," Doc explained. "Though you won't have to worry about getting sunburned by it because at this time the ozone layer is one-hundred percent intact with no air pollution around to harm it."
They flew a little further on until they noticed a small clear space in the jungle and slowly Doc began descending the Delorean down toward it.
"Well, now it is time for us to play the role of explorers and observe the ways and habits of our oldest ancestors, as soon as we can find them," Doc said.
"Gee, the air here is so clear and clean and warm and fresh," Marty said in awe as he took a deep breath of the air around them.
Doc breathed deeply in the air around them as well. He then quickly too a handkerchief out of his coat pocket before sneezing heavily into it, much to Marty's surprise.
"Are you allergic to something around here?" Marty asked with concern.
"I think it must be those prehistoric flowers growing over there," Doc sniffed as he pointed towards a patch of huge orange and yellow flowers near to the left side of them.
"So then let's start looking over here, away from them," Marty said as he gestured to a path to the right of them.
Doc nodded and said, "Good thinking, Marty."
So then they started off in the right direction. They walked on and on. They came across dozens of prehistoric plants which Doc pointed out to Marty as having seen before in pictures of fossils. They also found a lot of very large insects which Doc cautioned Marty to keep out of the way of and so he did.
Then all of a sudden they heard a little whimpering cry coming from somewhere behind the trees ahead of them.
"What's that?" asked Marty quietly.
"It sounds to me like the cry of a baby... or, more specifically, a baby Australopithecus Afarensis!" Doc said in an excited whisper.
"Do you think we should go see what's wrong with it?" asked Marty.
"Yes, I do," said Doc.
They then made their way through the trees and the thick underbrush for a short ways before they looked down and found the source of the crying. Sure enough, it looked like a baby chimpanzee but with somewhat more humanly shaped bones and facial features. It had its face scrunched up and its mouth was wide open as it was clearing wailing at the top of its little lungs.
"The poor little thing most be lost," Marty said very softly.
"I think so, too," replied Doc, "as it is certainly crying as only a human baby cries for its mother."
"So shouldn't we take it with us and try to find it's mother?" asked Marty.
Doc thought about this for a moment and then said, "I suppose so, yes. As I can't think of how that could disrupt the space-time-continuum in any way."
So then Marty went as quietly as he could up to the wailing baby and picked it up and cradled it in his arms and rocked it just as one would an actual human baby. It kicked its arms and legs and squirmed in Marty's hold of it for a while and then it slowly quieted and calmed down and held still.
"You see now how we've stayed the same in some ways," said Doc.
"Yes, I do," said Marty in awe.
"Come on now, let's go look for the baby's mother," Doc said.
They then began walking along the path and searched for any other signs of adult Australopithecus Afarensis'. Though they could find none.
"It's not like they'll be waiting for us to come them," Doc said thoughtfully. "So I think maybe we should try calling out for them to come to us."
"What do you mean?" asked Marty. "Like how?"
"I mean like this," said Doc. He then made a loud panting hoot sound that seemed to echo through the jungle. "It's the only for m of communication that we had at this time," he explained.
"I see," said Marty. "I bet I can do it." He then tried making the loud panting hoot sounds which he had heard chimps make in the zoo he had gone to. After a few moments he stopped and listened but could hear no response to it.
"I think we should keep going on," he said.
Doc nodded. "And keep that up by all means. You're doing great."
And so they continued onward while all the while making the panting and hooting sounds of chimps. They went on for a while until they suddenly heard a new sound. It wasn't a sound any chimp would make. It was a loud trumpeting sound rather like that of an elephant, only much deeper and louder.
They both stopped in their tracks. "What was that, Doc?" Marty asked a bit nervously.
"It sounds to me like the call of the prehistoric elephant," replied Doc quietly. "And they are three times as big as the ones we know of in our time. And a lot more dangerous, too."
"What do we do?" asked Marty.
"We go on quietly until we've passed by it and try not to do anything that could arouse it," Doc said very warningly.
So then they went on quietly for a time. Then they came in sight of the mighty elephant ancestor which looked extremely intimidating in its size and mass. They started to sneak past it when suddenly the baby in Marty's arms saw it and let out a frightened yell which it heard and began turning slowly around as it's ears perked up.
"Quick! Over here!" Doc whispered as he hurriedly led Marty over to where a large and thick tree was growing where they could hide behind.
They hid behind the tree while the elephant turned around and looked in all directions. They were quiet and seemingly safe. But then Marty spotted another path of the same wildflowers they had seen before that Doc had been allergic to.
Doc took out his handkerchief again and tried to sneeze into it as quietly as he could, but the elephant still heard it as it turned its head directly at them.
"Oh shit!" Marty uttered.
The elephant then gave a mighty roar with its trunk and charged toward them.
"Run for your life!" Doc exclaimed as he and Marty raced out of the way of the charging elephant's path. They darted away from the tree and cringed as they heard the sound of the tree splitting apart from the elephant knocking it over in its mad dash for them.
They ran and ran as fast as they could. They ran until they found they could run no further when they came to a long and wide lake that stretched before them.
"Do you think maybe we could wade across it?" asked Marty.
Doc was about to reply when all of a sudden a gigantic sized prehistoric crocodile rose out from beneath the water's surface. It began opening it's long and thickly toothed jaws as it slowly swam towards them.
"I don't think so," said Doc.
They just then heard the heavy thumping sounds of the elephant catching up to them.
"What do we do now, Doc?" Marty asked frantically.
Doc looked around fretfully and quickly spotted a set of long green vines growing down from the trees just beside them. He then made quick but careful calculations in his mind and then grabbed hold of one.
"Come with me, Marty! This way!" Doc exclaimed as climbed up the vine as high as he could and then swung it hard and swiftly across the lake and got off at the edge of it on the other side.
Marty the hurriedly grabbed hold of the vine, while still clutching the baby tightly against his chest with one arm, and climbed to the highest of it and then kicked off and swung himself forward with a loud Tarzan-like yell. He reached the other side of the lake safely and jumped off of the vine and joined Doc.
"Whew! That was a close one!" he said breathlessly and wiped the perspiration from his forehead.
"Too close for comfort," added Doc. "Come on."
They then went ahead further into the depths of the jungle. They walked on and on until it was near to sunset when they suddenly heard the sound of panting hoots coming from somewhere around them.
"Listen, Doc," whispered Marty. "I think I can hear the baby's mother in there."
The baby must have thought so too as it just then began making excited chattering noises and wiggled around in Marty's arms.
"Great Scott, you're right!" said Doc. "Come on."
They went a little further and then when they emerged from behind a tall thicket they found a group of Australopithecus Afarensis'. Most of them were sitting down and appeared to be grooming each other. There was one that looked to be almost certainly female who was sitting all alone and looking sad.
"That must be her," Marty whispered.
They then walked cautiously towards the group and Marty held out the baby as they got closer and when they reached the mother she gave a loud hoot and jumped up and seized her baby from Marty's arms.
"You were right," Doc said grinning.
Just then they heard another loud hoot. They turned and looked just in time to see a heavily muscular male throw a large rock at the back of another male. The other male then attacked the other and they began to wrestle with each other quite violently.
"What are they fighting for?" asked Marty curiously.
"For the role of the leader of the group," explained Doc. "It's the only way they know how to these days."
"That big one looks kind of like Biff Tannen," said Marty. "I guess some things really do never change much."
"I'm glad you understand more about evolution now," said Doc approvingly.
"I do," said Marty. "I also know how to write my essay."
"Good," said Doc. "Now let's get back to our own time."
And so they did. They found the Delorean actually not to far away from where they were and went back to Hill Valley in 1986.