The cold wind cut over a half-submerged tree stump enveloped in thick shards of ice, fine sand whipping the patches of snow that dotted the shoreline. We trooped down to the river's edge, single file.
       It was another day at the beach, circa 71,000 B.C.
        Thog had the point, and we all froze when he raised his right arm in a swift, fluid motion. Even the two little ones knew the drill. I swept the bleak terrain with my eyes. Thog was our best hunter. You trusted his warning.
        I followed Thog's line of sight and saw something moving behind a low-sloping hill 100 yards or so to the left. We sank to our knees, reindeer skins billowing over fur boots. I held a flint-tipped spear and carried a sack of dried meat. The wind stung a bit less, crouching down. It was around early September, but the night had already brought temperatures well below zero.
       I had long since forgotten my old idea of 'cold.' Here, Cold was like Hunger or the great cave bears that could rip you apart. Cold lived with you like another member of the clan. Cold talked to you and slept with you during the long, dark nights. You were never alone with Cold around.
        Cold wasn't the only thing keeping us company today.
        Whatever had moved on the side of the hill vanished. We remained hunkered down, the stiff breeze rippling our rough clothing.
       Cona, Thog's mate, minded the children. Uula fidgeted like any 11-year-old girl would. Dook kept quiet. Even swaddled in furs, he looked thin. Dook the young artist, was already skilled at embossing hunting scenes on rock walls. Dook the linguist could speak more refined sentences than the rest of the adults put together. Dook, the future of the human race, carried the mitochondrial DNA of Homo Sapiens that would lead to my modern world.
       Dook, was the reason I was here. The kid had to make it through the coming winter.
       Pusk, the other male of our tiny group, nudged closer to his older brother. "Lion?" He asked. "Bear?"
       "No," replied Thog. "Not see clear. Moved quick. Maybe they saw us."
       "They?" asked Pusk.
       "Not animals. Maybe..."
       Thog kept scanning the low hummock. A small creek ran through some stunted pines between us and the gently sloping hill. It emptied into the cold river that flowed northward, forking around a flat island in the distance. A long time from now, the tall shadow of the Eiffel Tower would fall upon a city of millions here. A very long time from now.
       Thog arose from his crouch and started working his way across the little creek. Pusk and I held back. When Thog got to the other side, he straightened and motioned for us to follow.
       Something about the way he stood was odd. Thog never slipped climbing a rock face; his was always the fatal blow to the mammoth's skull. In my time, Thog would have been a pro quarterback or the owner of a successful software company. Here, he just kept us alive.
       But something had surprised him.
       Pusk and I leapt across the little stream to join him. Cona and the kids stayed behind, sheltered by a clump of elderberry bushes shorn of fruit. Thog stared at a narrow defile in the low hummock.
       "Grunters," he said with faint awe.
       A pair of shadows detached themselves from the dried brush that bowed in the stiff breeze at the base of the little canyon. Short, clad in furs that hung loosely over their squat bodies, the two regarded us warily. They held thick spears of sharpened wood with no stone tips.
       Neanderthals. There weren't supposed to be any still alive.
       The anthropology training I'd received before being sent back to this glacial age claimed modern humans were related to my tiny tribe's Cro-Magnon. Neanderthals were an evolutionary dead end, extinct by the time the last great ice sheets scoured northern Europe clean. The more primitive Neanderthals couldn't compete with the Cro-Mags' superior weaponry and were doomed when the environment changed yet again for the worse.
       But there they were. Non-extinct. Watching us.
       Thog paused another moment, then raised his left arm while burying his spear point in the hard, cold soil. That meant "No threat. And you?" in the amazingly expressive body language of the clan.
       Pusk hissed at him. "You crazy? What might they do?"
        "Same we might do," said Thog.
       The Neanderthals kept watching us.
       "Our father's father's father told of Grunters," said Thog. "Said, 'Long gone.'"
       "Not so long gone," muttered Pusk.
       I glanced back at Cona and the kids. Uula was huddled close to her mother, but the boy craned his neck to see what the adult males were so excited about. Dook wanted to see and touch everything. He learned so fast, soaking up experiences like a sponge.
       The two Neanderthals straightened a little. And then they slowly, carefully, made their way forward. I could see their thick noses and sloped foreheads, dark coarse hair tossed by the stiff breeze. They reminded me of stone-age Yogi Berras.
       We wore roughly sewn reindeer tunics and bison trousers, but our clothes were Gucci compared to theirs. The Yogis' animal skins hung loose on them, barely covering their upper bodies. They had fur leggings but lashed with strips of hide rather than sewn together with twine. And they were barefoot! As the Yogis slowly came our way, I could tell one was walking with a limp. Gimpy or not, I didn't want to tangle with him. He stood about five-four, but the knotted muscles jostling under his crude clothing were those of a comic book superhero.
       "Thog?" asked Pusk.
       Thog let his spear fall. The echo of it clattering onto the stones of the creek bed carried in the cold wind. The Neanderthal pair straightened some more and then cocked their heads in a very human way.
       Thog turned to Pusk.
       "Maybe not good idea?" said Pusk.
       Thog looked at me. I dropped my spear as well.
       Pusk shook his head and then let his weapon fall to the rocky ground.
       The Neanderthals looked at us, then over to the brush where Cona and the kids were hiding. Dook had made his way just out of reach of his mother's grasp and was staring at them. Above, a tern called in the thin, cold air.
       "Dook," called Thog, extending his arm. The Neanderthals watched as the boy left his mother and sister and bounded across the little stream to us. Dook looked up at Thog as Pusk stood by nervously.
       "Food," Thog said to me, and I understood what he wanted to do.
       So did Pusk. "NOT good idea!"
       I set my sack down and fumbled for the hunks of dried bison meat wrapped in dried grass inside. It had been a tough hunt, and only Thog's skill had kept me from getting trampled by a wounded bull. I wondered briefly if he thought I was more trouble than I was worth. My hunting skills were pathetic, and I was an oaf with stone tools.
       At least the kids seemed to like me.
       I pulled out a couple of dark clumps of protein. Dried bison tasted like varnished wood flooring but not as chewy. The Yogis watched us carefully. Dook took a couple of hunks of withered meat in his small hands and studied them.
       "I will give this to them," the boy said to his father in a soft but confident voice. "They are hungry, too. We can be friends. Even with 'grunters'."
       "Even with grunters," said Thog as he looked at his son with ageless pride.
       My job was to protect Dook, to make sure he carried on his vibrant talents. But he was doing more to teach me what it was like to be human.
       "Me hungry too," said Pusk as Dook walked over to the Neanderthals. They had laid down their crude spears and were watching the boy's approach. Dook laid down the meat before them, and I could see his smile returned in the faces of the two Yogis. I realized they were father and son and that there probably wasn't a mate for the younger Neanderthal.
       This was the end for them.
       Maybe it was the beginning for us. Eons before the rise of religion, faith and society, Thog and Dook were taking the first steps to make modern man moral. A simple act of kindness towards our ancestors on the shore of the prehistoric River Seine.
       Maybe I wasn't given this mission in time because of what I could do for them. Perhaps I was here because of what they could do for me.
       And what I'd take back.
       Both the Yogis reached out gently to touch Dook. He calmly let them stroke his hair and ruffle the fur of his parka. Then, the Neanderthals gathered up the small bundles of meat and, with moist eyes, turned away from our little party.
       Dook stood apart, watching them make their way through the dry scrub brush of the little gully until they were out of sight.
       The wind picked up, and cold sand bit my exposed skin. A long way off, a saber-tooth tiger coughed. And the river flowed north into the ancient sea.