Susan's finger was still on Le'an's gums; the flesh was indeed harder than it had been a couple of days ago. Just as she was about to call Chen Hao to come and look, she heard the child make a gurgling sound in his throat, as if he were playing with saliva in his mouth.

“He seems to be making a sound,” Susan said softly.

Chen Hao was squatting by the crib looking for the dropped pacifier, without looking up: "Is he going to spit up? Last time I fed him, he hiccuped like a tractor."

As soon as she finished speaking, Le'an's face suddenly scrunched up, her mouth opened, and she let out a short "Awoo".

Then, his eyes crinkled into a smile.

It wasn't crying, nor was it hiccups; it was a genuine laugh.

Chen Hao froze, forgetting to pick up the pacifier from his hand: "He...smiled?"

Carl looked up from his notebook, his pen pausing. He quickly turned to a new page and wrote down the time: 9:17 AM.

Nana's voice then rang out: "Facial muscle coordination changes were detected. The corners of the mouth turned up by 32 percent, and the eye wrinkles match the characteristics of a social smile. This is determined to be the first recognizable smile, lasting 1.6 seconds."

"He laughed, didn't he?" Chen Hao suddenly stood up, bumping into the bed rail. "Am I seeing things? He really laughed just now?"

Susan was also stunned, her fingers slowly leaving Le'an's cheek. She looked into her son's eyes, those eyes that still couldn't see clearly, yet they were curving straight in her direction.

“He smiled at me,” she said.

"Bullshit!" Chen Hao slapped his thigh. "He clearly looked at me first! I was wandering around here for ages before he even smiled! This is like him recognizing his father!"

“According to eye-tracking data,” Nana calmly added, “the infant’s gaze originates in the father’s left shoulder area, then shifts to the mother’s face, and the focus is on the mother’s direction when a smile is triggered.”

"Look, look!" Chen Hao pointed at Nana, "Even the robot said he looked at me first!"

Susan ignored him, simply picking Le'an up gently and holding her close to her chest. The child's little hands twitched in the air before finally resting on her arm.

“He’s especially energetic today,” she said.

Carl closed his notebook and walked closer: "Normal. Increased saliva production and gingival hardening are typical signs of pre-teething, accompanied by accelerated neurodevelopment and improved emotional expression. More interactive behaviors are expected in the next two weeks."

"For example?" Chen Hao leaned closer.

"For example, repeating sounds, actively tracking moving objects, and reacting to familiar sounds."

"Then it can talk?" Chen Hao's eyes lit up.

“No,” Carl said expressionlessly. “It just means his brain is starting to work.”

"Oh dear, the way you're saying it makes it sound like my son was a stone before."

Nana has already started accessing the knowledge base, and the infant language development cycle chart is scrolling on the screen. "At this stage, it should mainly focus on 'babbling,' which is the prelude to speech. It is recommended that family members talk to the baby more to stimulate the auditory feedback circuit."

“Then I’ll do it.” Chen Hao immediately sat down on the edge of the bed, leaned close to Le’an’s face, and said, “Hey! Kid! Call me Dad! Dad—Dad—”

He drew out the sound, his face turning red.

Le'an stared at him, then suddenly opened her mouth, letting out a string of "ee-ya ee-ya" sounds, with a slight bend at the end.

"Did you hear that!" Chen Hao jumped up. "He said 'Dad'! The last syllable was definitely 'Dad'!"

“That’s ‘ah’,” Carl said.

"He's responding to me!" Chen Hao persisted. "If you don't believe me, record it and play it for aliens. They'll say it sounds like 'Dad' too."

“I’ve already recorded it,” Nana said. “The audio sample has been archived, numbered b-0996-01, and labeled as ‘suspected early voice attempt’.”

Susan held the baby and gently rocked him, her lips never leaving his mouth. She looked down at Le'an's little mouth and noticed that his lower lip was a little wet, and he was constantly blowing small bubbles.

“He’s just drooling again,” she said.

“This is normal.” Carl flipped through his notebook. “Increased salivary gland activity helps with oral antibacterial activity and food pre-digestion. Although he’s not eating yet.”

"Wait until he actually grows teeth, then let's see if you'll still talk so casually," Chen Hao muttered. "He'll bite you in the middle of the night and see what happens."

As they were talking, Le'an made another "cluck" sound, this time clearer, as if it had come out from deep in her throat.

The four people fell silent for two seconds.

“He smiled again,” Susan said.

"This time it's three seconds," Nana counted. "The frequency of the laughter is close to the range of human pleasure response."

Chen Hao snatched the phone, turned on the recording function, and pointed it at Le'an's face: "Come on, smile again! Give Dad a complete performance!"

He made a face, stuck out his tongue, and looked at the sky sideways.

Le'an stared at him, then suddenly raised her leg and kicked hard twice.

"Ouch!" Chen Hao dodged backward. "He kicked me! You've gone too far!"

“Motor coordination is also improving,” Carl noted. “Lower limb explosive power is increasing, and the kicking trajectory is repetitive and regular, which may indicate an intention to express emotions.”

“He was just insulting me,” Chen Hao said, rubbing his knee. “This kid holds a grudge too much.”

Susan laughed out loud: "Don't scare him."

"What did I scare him about? This is just parent-child interaction! Don't you understand scientific parenting?"

“Then your face just now,” Susan shook her head, “would make anyone cry.”

Nana suddenly said, "I suggest we establish a growth record system. We already have three milestone events: first smile, first vocalization, and spontaneous physical response. If we don't archive them regularly, we might miss key milestones."

“How about keeping a diary?” Susan said. “Write down one thing you can remember each day.”

“Okay,” Nana replied. “I will generate an electronic file simultaneously, which includes time, physiological data, and environmental parameters.”

“I use a research format for my activity log,” Carl said, “to ensure traceability and analytical value.”

"And what about me?" Chen Hao asked.

“You’re in charge of providing the materials,” Susan said. “For example, that funny face we just saw is very valuable for research.”

"Hey!"

The family quieted down. Sunlight streamed through the curtains, falling on the crib railings. Le'an lay in Susan's arms, her eyelids drooping, her little hands still clutching the hem of Susan's clothes.

“He laughed twice this morning,” Susan said softly, “once at me, and once at you.”

"And there was another time I tried to hit the ceiling," Chen Hao added. "That counts too."

“No,” Carl said.

"How do you know everything?"

"I just won't say it."

Nana's screen flickered, and a new folder automatically popped up: 【Le'an's Growth Record - Day 32】. It already contained three entries:

1. 09:17, First social smile, to: Mother

2. At 09:19, a non-crying guttural sound was emitted, lasting 2.1 seconds.

3. 09:21, Active leg kicking reaction, triggered by: Father's facial contortion.

"I need to write it down too." Chen Hao took out his phone's memo app and opened it to create a new note.

He typed a few words, deleted them, and then typed again.

Finally, I wrote: "My son smiled today and ignored me."

Susan glanced at it: "Can't you write something nicer?"

“That’s called being real.” Chen Hao put away his phone. “Show him this later, so he knows that his father was ignored from the very beginning.”

“You can show off when he can call people,” Susan leaned back on the sofa.

"I'll wait." Chen Hao sat down next to her and reached out to pat Le'an's head. "You'd better grow up quickly, or I'll be old."

Le'an hummed in her sleep, her little mouth moving as if she was chewing something.

Carl wrote down: "Day 32, morning, chewing-like movements observed, frequency six times per minute, presumably related to gum discomfort. Safety chewable is recommended."

Nana updated the database and uploaded all of today's records to the family cloud drive, naming it: [Early Signs of Growth].

Susan gently placed Le'an into the crib and covered him with a small blanket. His hands were still moving, sometimes gripping the railing, sometimes letting go.

“He doesn’t want to sleep,” she said.

“Then let’s stay awake with him.” Chen Hao sat cross-legged on the edge of the bed. “Anyway, I have nothing else to do.”

"You said you were going to do laundry yesterday."

"Not today, I have to protect the future of human civilization."

"You can't even find your own socks."

That's because they're too cunning.

Carl closed his notebook and stood up: "I'll go organize today's records."

"Wait a minute," Chen Hao called out to him, "What other changes do you think he might undergo in the future?"

Carl turned around: "Within three months, he can roll over, recognize people, and make the 'ba' and 'ma' syllables. Around six months, he may be able to sit up steadily and start trying to crawl."

"When can he play games?" Chen Hao asked.

“I don’t know,” Carl said, “but with your hand speed, you definitely wouldn’t have time to teach him how to play King of Glory.”

That's a personal attack.

Nana interjected, "Based on current developmental trends, the baby is predicted to laugh again within 72 hours. We recommend maintaining the frequency of interaction to increase the probability of triggering laughter."

"Then I'll make another funny face later." Chen Hao rubbed his hands together, eager to try.

“Don’t scare him,” Susan said.

"I'll be gentler."

Le'an rolled over in bed, lying face down with her bottom sticking up like a little frog.

"What is he doing?" Chen Hao asked, his eyes wide.

Carl quickly flipped open the manual: "It could be an increased prone reflex, or it could be... preparing to roll over."

Before the words were even finished, Le'an braced herself with her little arms, lifted her head, and flipped herself over, face up, eyes open, and making an "oh" sound.

All four of them were stunned.

"He..." Chen Hao swallowed hard. "Did he just turn over by himself?"

Carl glanced at his watch: "Record time: 10:03 AM. First successful independent rollover, taking 1.8 seconds."

Nana immediately announced: "Milestone event update. Growth progress increased by one level."

Susan had already taken out her phone to take a picture, her hand trembling slightly.

“He can really move now,” she said.

Chen Hao stared blankly at his son, suddenly feeling a lump in his throat. He reached in and gently touched Le'an's face.

The child winked at him, then opened his mouth and let out a long "Ah—".

It's like they're saying hello.